foo.cc: In function 'int main()':
foo.cc:11:15: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     for (i=0;i<strlen(s);i++)
      |              ~^~~~~~~~~~
foo.cc:10:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 |     scanf("%s",s);
      |     ~~~~~^~~~~~~~
foo.cc:6:10: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
    6 |     char c,s[505];
      |          ^

[Hydro](https://hydro.ac)提供评测服务