foo.cc: In function 'void solve(char*, char*)':
foo.cc:12:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0;i<strlen(s);i++)
             ~^~~~~~~~~~
foo.cc:31:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(j=0;j<strlen(s);j++)
          ~^~~~~~~~~~
foo.cc:11:10: warning: unused variable 'k' [-Wunused-variable]
  int i,j,k;
          ^
foo.cc: In function 'int main()':
foo.cc:45:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s",s);
     ~~~~~^~~~~~~~

[Hydro](https://hydro.ac)提供评测服务