/in/foo.cc: In function 'int main()':
/in/foo.cc:20:7: error: 're' was not declared in this scope
   for(re i=1;i<=n;i++){
       ^~
/in/foo.cc:20:14: error: 'i' was not declared in this scope
   for(re i=1;i<=n;i++){
              ^
/in/foo.cc:25:23: error: 'memset' was not declared in this scope
   memset(s,0,sizeof(s));
                       ^