/in/foo.c: In function 'main':
/in/foo.c:33:6: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
  len=strlen(strs);
      ^~~~~~
/in/foo.c:33:6: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:33:6: note: include '<string.h>' or provide a declaration of 'strlen'
/in/foo.c:50:9: warning: too many arguments for format [-Wformat-extra-args]
  printf("Impossible!",times);
         ^~~~~~~~~~~~~