/in/foo.cc: In function 'int main()':
/in/foo.cc:39:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<=strlen(s1)-1;++i){
                ^
/in/foo.cc:42:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(j=1;j<=strlen(s2)-1;++j){
              ^
/in/foo.cc:47:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if(j==strlen(s2)){
         ^