foo.cc: In function 'int main()':
foo.cc:14:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<strlen(s);i++)
              ~^~~~~~~~~~
foo.cc:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s",s);
     ~~~~~^~~~~~~~
foo.cc:9:10: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
     char c,s[505];
          ^

[Hydro](https://hydro.ac)提供评测服务