/in/foo.cc: In function 'int main()':
/in/foo.cc:9:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0;i<strlen(s);i++){
                ^
/in/foo.cc:10:9: warning: unused variable 't' [-Wunused-variable]
    char t=s[i];
         ^