foo.cc: In function 'void solve()':
foo.cc:18:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     for(int i=1;i<=a.size();i++)f[i][0]=i;
      |                 ~^~~~~~~~~~
foo.cc:19:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for(int i=1;i<=b.size();i++)f[0][i]=i;
      |                 ~^~~~~~~~~~
foo.cc:20:18: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |     for(int i=1;i<=a.size();i++){
      |                 ~^~~~~~~~~~
foo.cc:21:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int j=1;j<=b.size();j++){
      |                     ~^~~~~~~~~~

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