foo.cc: In function 'int main()':
foo.cc:9:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    9 |     for(int i=0;i<s.length();i++) if(s[i]=='5') v.push_back(i);
      |                 ~^~~~~~~~~~~
foo.cc:12:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     for(int i=1;i<v.size();i++) ans=ans-(v[i]-v[i-1])*(v[i]-v[i-1]-1)/2;
      |                 ~^~~~~~~~~

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