/in/foo.cc:12:27: error: 'Edge' does not name a type
     bool operator <(const Edge& W) const {
                           ^~~~
/in/foo.cc: In member function 'bool pp::operator<(const int&) const':
/in/foo.cc:13:22: error: request for member 'w' in 'W', which is of non-class type 'const int'
         return w < W.w ;
                      ^
/in/foo.cc: At global scope:
/in/foo.cc:20:10: error: '::main' must return 'int'
 int main(){
          ^