ninth exercise

1-9.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+int main() {
+  int c;
+  int prevb = 0;
+  while ((c=getchar()) != EOF){
+    if (c == ' ' && prevb == 1){
+      continue;
+    }
+    if (c == ' '){
+      prevb = 1;
+      putchar(c);
+    }
+    else{
+      prevb = 0;
+      putchar(c);
+    }
+  }
+  return 0;
+}