foo.cc: In function 'int main()':
foo.cc:57:5: error: 'cin' was not declared in this scope
     cin>>m>>n;
     ^~~
foo.cc:57:5: note: suggested alternative: 'main'
     cin>>m>>n;
     ^~~
     main
foo.cc:61:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<s.size();j++)
                     ~^~~~~~~~~
foo.cc:68:17: error: 'cout' was not declared in this scope
     if(cnt==2)  cout<<"5";
                 ^~~~
foo.cc:68:17: note: suggested alternative: 'cnt'
     if(cnt==2)  cout<<"5";
                 ^~~~
                 cnt
foo.cc:69:17: error: 'cout' was not declared in this scope
     if(cnt==1)  cout<<"6";
                 ^~~~
foo.cc:69:17: note: suggested alternative: 'cnt'
     if(cnt==1)  cout<<"6";
                 ^~~~
                 cnt
foo.cc:70:17: error: 'cout' was not declared in this scope
     if(cnt==9)  cout<<"63";
                 ^~~~
foo.cc:70:17: note: suggested alternative: 'cnt'
     if(cnt==9)  cout<<"63";
                 ^~~~
                 cnt
foo.cc:71:17: error: 'cout' was not declared in this scope
     if(cnt==11) cout<<"65";
                 ^~~~
foo.cc:71:17: note: suggested alternative: 'cnt'
     if(cnt==11) cout<<"65";
                 ^~~~
                 cnt
foo.cc:72:18: error: 'cout' was not declared in this scope
     if(cnt==12)  cout<<"69";
                  ^~~~
foo.cc:72:18: note: suggested alternative: 'cnt'
     if(cnt==12)  cout<<"69";
                  ^~~~
                  cnt

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。