/*
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*/
#include "bits/stdc++.h"
using namespace std;
#define ok1 printf("ok1\n")
#define ok2 printf("ok2\n")
#define M LLONG_MAX
#define rep(i,n) for(int i=0;i<n;++i)
#define REP(i,s,n) for(int i=(s);i<(n);++i)
#define repr(i,n) for(int i=n-1;i>=0;--i)
#define REPR(i,s,n) for(int i=(s);i>=(n);--(i))
#define all(a) (a).begin(),(a).end()
#define reall(a) (a).rbegin(),(a).rend()
#define pb emplace_back //emplace_backの方が速いが使い慣れてないため
#define DOUBLE fixed << setprecision(15)
#define fi first
#define se second
#define mp make_pair
#define mt make_tuple
#define BIT(n,m)(((n)>>(m))&1)
const double pi = acos(-1.0);
typedef vector<int> vi;
typedef vector<string> vs;
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<char> vc;
typedef vector<double> vd;
typedef vector<bool> vb;
typedef deque<ll> dll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> TLL;
typedef vector<P> vP;
typedef vector<TLL> vTLL;
const ll mod = 1e9 + 7;
//const ll mod = 998244353;
ll dy[4] = { 1,0,-1,0 };
ll dx[4] = { 0,1,0,-1 };
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class A, class B>
ostream& operator<<(ostream& ost, const pair<A, B>&p) {
	ost << "{" << p.first << ", " << p.second << "} ";
	return ost;
}
template<class T>
ostream& operator<<(ostream& ost, const vector<T>&v) {
	ost << "{";
	for (int i = 0; i<v.size(); i++) {
		if (i)ost << ", ";
		ost << v[i];
	}
	ost << "} ";
	return ost;
}
template<class A, class B>
ostream& operator<<(ostream& ost, const map<A, B>&v) {
	ost << "{";
	for (auto p:v) {
		ost << "{" << p.first << ", " << p.second << "} ";
	}
	ost << "} ";
	return ost;
}
bool out_check(ll a, ll b) { return (0 <= a && a < b); }
void addmod(ll &a, ll &b) { a = (a + b) % mod; }
double pitagoras(ll a, ll b, ll c, ll d) {
	double dx = a - b, dy = c - d;
	return pow(dx * dx + dy * dy, 0.5);
}
ll powmod(ll a, ll b) { ll c = 1; while (b > 0) { if (b & 1) { c = a * c%mod; }a = a * a%mod; b >>= 1; }return c; }
void Yes(bool x) { cout << ((x) ? "Yes\n" : "No\n"); }
void YES(bool x) { cout << ((x) ? "YES\n" : "NO\n"); }
void yes(bool x) { cout << ((x) ? "yes\n" : "no\n"); }
void Yay(bool x) { cout << ((x) ? "Yay!\n" : ":(\n"); }
vector<string> DAY = { "SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT" };
ll  n, m, d, e, r, l, k, h, Q, ans, ret = M;
bool flag = false, flag2 = false, flag3 = false;
string s, t, u;

class WeightedUnionFind {
public:
	int n;
	vector<int> u;
	vector<long long> weight;
	WeightedUnionFind(int n = 0) :n(n) {
		u = vector<int>(n);
		weight = vector<long long>(n, 0);
		for (int i = 0; i < n; i++)u[i] = i;
	}
	int r(int x) {
		if (u[x] == x)return x;
		r(u[x]);
		weight[x] += weight[u[x]];
		return u[x] = r(u[x]);
	}

	long long dif(long long x, long long y) {
		if (r(x) != r(y))return LLONG_MAX;
		return weight[x] - weight[y];
	}

	//x - y == w
	bool isOK(int x, int y, long long w) {
		if (r(x) != r(y))return false;
		return dif(x, y) == 0;
	}

	void unite(int x, int y, long long w) {
		r(x);
		r(y);
		w += weight[y];
		w -= weight[x];
		x = r(x);
		y = r(y);
		u[x] = y;
		weight[x] = w;
	}
};


int main() {
	//cin.tie(0); ios::sync_with_stdio(false);//not intractive
	cin >> n >> Q;
	WeightedUnionFind tree(n);
	rep(_, Q) {
		cin >> d;
		if (d) {
			ll x, y; cin >> x >> y;
			ans = tree.dif(x, y);
			if (ans == M) cout << "?\n";
			else cout << ans << endl;
		}
		else {
			ll c, x, y; cin >> c >> x >> y;
			tree.unite(c, x, y);
		}
	}
}


Measured memory_bytes: 4956