foo.cc: In function 'int main()':
foo.cc:10:15: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   10 |  for(int i=0;i<strlen(s);i++)
      |              ~^~~~~~~~~~
foo.cc:8:10: warning: unused variable 'b' [-Wunused-variable]
    8 |  int a=0,b=0;
      |          ^

[Hydro](https://hydro.ac)提供评测服务