aoj-dsl-1-b.test.cpp

// competitive-verifier: PROBLEM http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_1_B

#include "../../template/template.hpp"

#include "../../structure/union-find/weighted-union-find.hpp"

int main() {
  int N, M;
  cin >> N >> M;
  WeightedUnionFind< int > tree(N);
  while(M--) {
    int A, B, C, D;
    cin >> A >> B >> C;
    if(A == 0) {
      cin >> D;
      tree.unite(B, C, D);
    } else {
      if(tree.find(B) == tree.find(C)) {
        cout << tree.diff(B, C) << endl;
      } else {
        cout << "?" << endl;
      }
    }
  }
}