diff --git a/src/bin/bimood/main.rs b/src/bin/bimood/main.rs
index 80ff27b..84a1bb1 100644
--- a/src/bin/bimood/main.rs
+++ b/src/bin/bimood/main.rs
@@ -18,7 +18,7 @@ fn send<T: Write>(w: &mut T, f: &Frame) -> std::io::Result<()> {
     w.flush()
 }
 
-const DEFAULT_LOOP_TIME: usize = 120;
+const DEFAULT_ARG: usize = 120;
 const MIN_LOOP_TIME: usize = 20;
 
 fn main() -> std::io::Result<()> {
@@ -27,10 +27,12 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<usize>().unwrap();
     let y_size = args[2].parse::<usize>().unwrap();
-    let loop_time = args[3]
-        .parse::<usize>()
-        .unwrap_or(DEFAULT_LOOP_TIME)
-        .max(MIN_LOOP_TIME);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
+    let loop_time = arg.max(MIN_LOOP_TIME);
     eprintln!(
         "screen size {}x{}, loop time {:?}s",
         x_size, y_size, loop_time
diff --git a/src/bin/cnoise/main.rs b/src/bin/cnoise/main.rs
index c3baea1..a0a1720 100644
--- a/src/bin/cnoise/main.rs
+++ b/src/bin/cnoise/main.rs
@@ -48,7 +48,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<usize>().unwrap();
     let y_size = args[2].parse::<usize>().unwrap();
-    let arg = args[3].parse::<usize>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let t_frame = 0.040; // s
diff --git a/src/bin/dualmaze/main.rs b/src/bin/dualmaze/main.rs
index f9378bb..a57d7d6 100644
--- a/src/bin/dualmaze/main.rs
+++ b/src/bin/dualmaze/main.rs
@@ -240,7 +240,7 @@ where
     }
 }
 
-const DEFAULT_ARG: isize = 16;
+const DEFAULT_ARG: usize = 10;
 
 fn main() -> std::io::Result<()> {
     let args = args().collect::<Vec<_>>();
@@ -248,7 +248,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<i64>().unwrap();
     let y_size = args[2].parse::<i64>().unwrap();
-    let arg = args[3].parse::<isize>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();
diff --git a/src/bin/life/main.rs b/src/bin/life/main.rs
index c1c9f61..7a9c408 100644
--- a/src/bin/life/main.rs
+++ b/src/bin/life/main.rs
@@ -68,7 +68,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<usize>().unwrap();
     let y_size = args[2].parse::<usize>().unwrap();
-    let arg = args[3].parse::<u64>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<u64>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();
diff --git a/src/bin/lorenz/main.rs b/src/bin/lorenz/main.rs
index 03a11d1..41a131e 100644
--- a/src/bin/lorenz/main.rs
+++ b/src/bin/lorenz/main.rs
@@ -28,7 +28,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<usize>().unwrap();
     let y_size = args[2].parse::<usize>().unwrap();
-    let arg = args[3].parse::<usize>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();
diff --git a/src/bin/matrix-code/main.rs b/src/bin/matrix-code/main.rs
index 6472287..8f79066 100644
--- a/src/bin/matrix-code/main.rs
+++ b/src/bin/matrix-code/main.rs
@@ -191,7 +191,11 @@ fn main() -> Result<(), Box<dyn error::Error>> {
 
     let x_size = args[1].parse::<usize>().unwrap();
     let y_size = args[2].parse::<usize>().unwrap();
-    let arg = args[3].parse::<u64>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<u64>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();
diff --git a/src/bin/maze/main.rs b/src/bin/maze/main.rs
index 9c796ce..b124476 100644
--- a/src/bin/maze/main.rs
+++ b/src/bin/maze/main.rs
@@ -239,7 +239,7 @@ where
     }
 }
 
-const DEFAULT_ARG: isize = 16;
+const DEFAULT_ARG: usize = 10;
 
 fn main() -> std::io::Result<()> {
     let args = args().collect::<Vec<_>>();
@@ -247,7 +247,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<i64>().unwrap();
     let y_size = args[2].parse::<i64>().unwrap();
-    let arg = args[3].parse::<isize>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();
diff --git a/src/bin/predprey/main.rs b/src/bin/predprey/main.rs
index d48e635..fc8257e 100644
--- a/src/bin/predprey/main.rs
+++ b/src/bin/predprey/main.rs
@@ -76,7 +76,11 @@ fn main() -> std::io::Result<()> {
 
     let x_size = args[1].parse::<i64>().unwrap();
     let y_size = args[2].parse::<i64>().unwrap();
-    let arg = args[3].parse::<usize>().unwrap_or(DEFAULT_ARG);
+    let arg = if let Some(s) = args.get(3) {
+        s.parse::<usize>().unwrap_or(DEFAULT_ARG)
+    } else {
+        DEFAULT_ARG
+    };
     eprintln!("screen size {}x{}, arg {}", x_size, y_size, arg);
 
     let mut rng = thread_rng();