This documentation is automatically generated by online-judge-tools/verification-helper
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_1_B"
#include "../../template.h"
#include "../DSU/DSU_weighted.h"
void solve() {
int n, q; cin >> n >> q;
WeightedDSU<long long> dsu(n);
while (q--) {
int typ; cin >> typ;
if (typ == 0) {
int x, y, z; cin >> x >> y >> z;
// f[y] = f[x] + z
dsu.merge(x, y, z);
} else {
int x, y; cin >> x >> y;
if (dsu.getRoot(x) == dsu.getRoot(y)) {
cout << dsu.weight(y) - dsu.weight(x) << '\n';
} else {
cout << "?\n";
}
}
}
}
#line 1 "DataStructure/test/aizu_dsl_1_b_dsu_weighted.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DSL_1_B"
#line 1 "template.h"
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
#define EACH(it,a) for(__typeof(a.begin()) it = a.begin(); it != a.end(); ++it)
#define DEBUG(x) { cout << #x << " = "; cout << (x) << endl; }
#define PR(a,n) { cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl; }
#define PR0(a,n) { cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl; }
#define sqr(x) ((x) * (x))
// For printing pair, container, etc.
// Copied from https://quangloc99.github.io/2021/07/30/my-CP-debugging-template.html
template<class U, class V> ostream& operator << (ostream& out, const pair<U, V>& p) {
return out << '(' << p.first << ", " << p.second << ')';
}
template<class Con, class = decltype(begin(declval<Con>()))>
typename enable_if<!is_same<Con, string>::value, ostream&>::type
operator << (ostream& out, const Con& con) {
out << '{';
for (auto beg = con.begin(), it = beg; it != con.end(); it++) {
out << (it == beg ? "" : ", ") << *it;
}
return out << '}';
}
template<size_t i, class T> ostream& print_tuple_utils(ostream& out, const T& tup) {
if constexpr(i == tuple_size<T>::value) return out << ")";
else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup);
}
template<class ...U> ostream& operator << (ostream& out, const tuple<U...>& t) {
return print_tuple_utils<0, tuple<U...>>(out, t);
}
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
long long get_rand(long long r) {
return uniform_int_distribution<long long> (0, r-1)(rng);
}
template<typename T>
vector<T> read_vector(int n) {
vector<T> res(n);
for (int& x : res) cin >> x;
return res;
}
void solve();
int main() {
ios::sync_with_stdio(0); cin.tie(0);
solve();
return 0;
}
#line 1 "DataStructure/DSU/DSU_weighted.h"
template<class S>
struct WeightedDSU {
std::vector<int> lab;
std::vector<S> w; // relative to parent
WeightedDSU(int n) : lab(n, -1), w(n) {}
int getRoot(int u) {
if (lab[u] < 0) return u;
return getRoot(lab[u]);
}
int weight(int u) {
if (lab[u] < 0) return w[u];
return w[u] + weight(lab[u]);
}
// weight(t) = weight(s) + diff
// returns false if contradicts
bool merge(int s, int t, S diff) {
// jump to root
diff = diff + weight(s) - weight(t);
s = getRoot(s);
t = getRoot(t);
if (s == t) return diff == 0;
if (lab[s] > lab[t]) {
std::swap(s, t);
diff = -diff;
}
lab[s] += lab[t];
lab[t] = s;
w[t] = diff;
return true;
}
};
#line 5 "DataStructure/test/aizu_dsl_1_b_dsu_weighted.test.cpp"
void solve() {
int n, q; cin >> n >> q;
WeightedDSU<long long> dsu(n);
while (q--) {
int typ; cin >> typ;
if (typ == 0) {
int x, y, z; cin >> x >> y >> z;
// f[y] = f[x] + z
dsu.merge(x, y, z);
} else {
int x, y; cin >> x >> y;
if (dsu.getRoot(x) == dsu.getRoot(y)) {
cout << dsu.weight(y) - dsu.weight(x) << '\n';
} else {
cout << "?\n";
}
}
}
}