/in/foo.cc: In function 'int main()':
/in/foo.cc:11:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(int i=0;i<s.size();i++){
                  ~^~~~~~~~~
/in/foo.cc:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<c.size();j++){
                     ~^~~~~~~~~
/in/foo.cc:28:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 for(int j=0;j<c.size();j++)if(c[j]>='A'&&c[j]<='Z')ss[c[j]-'0']++;//求频率最高 
                             ~^~~~~~~~~
/in/foo.cc:42:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                     for(int j=0;j<c.size();j++){
                                 ~^~~~~~~~~
/in/foo.cc:54:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                     for(int j=0;j<c.size();j++){
                                 ~^~~~~~~~~
/in/foo.cc:68:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j=0;j<c.size();j++){
                         ~^~~~~~~~~
/in/foo.cc:75:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
          for(int i=0;i<s.size();i++){
                      ~^~~~~~~~~