#pragma region Macro
#pragma region Basic
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
#define REP(i, n) for (int i = 0, i##_len = (n); i < i##_len; ++i)
#define FOR(i, a, b) for (int i = (a), i##_len = (b); i < i##_len; i++)
#define FORD(i, a, b) for (int i = (a), i##_len = (b); i > i##_len; i--)
#define FORR(t, a) for (auto t : a)
#define ALL(x) (x).begin(), (x).end()  // sortなどの引数を省略したい
#define GET(i, j) get<j>(i)
#define MT(x, ...) make_tuple(x, __VA_ARGS__)
#define SZ(x) ((int)(x).size())
#define ZERO(x) memset(x, 0, sizeof(x))
#define FILL(x, y) memset(x, y, sizeof(x))
#define PB push_back
#define EB emplace_back
#ifdef _DEBUG
#define PRE_COMMAND             \
    std::cin.rdbuf(in.rdbuf()); \
    cout << fixed << setprecision(15);
#else
#define PRE_COMMAND cout << fixed << setprecision(15);
#endif
const double EPS = 1e-10;
const double PI = acos(-1.0);
template <class T>
auto MAX(T& seq) {
    return *max_element(seq.begin(), seq.end());
}
template <class T>
auto MIN(T& seq) {
    return *min_element(seq.begin(), seq.end());
}
template <class T>
auto SUM(T& seq) {
    T temp{0};
    auto& temp2 = temp[0];
    return accumulate(seq.begin(), seq.end(), temp2);
}
template <class T>
void SORT(T& seq) {
    sort(seq.begin(), seq.end());
}
template <class T, class S>
void SORT(T& seq, S& sort_order) {
    sort(seq.begin(), seq.end(), sort_order);
}
template <class T>
void SORTR(vector<T>& seq) {
    sort(seq.begin(), seq.end(), greater<T>());
}
template <class T>
void CHMAX(T& a, const T& b) {
    if (a < b) { a = b; }
}
template <class T>
void CHMIN(T& a, const T& b) {
    if (b < a) { a = b; }
}
template <class T>
set<T> VECTOR_2_SET(vector<T>& v) {
    set<T> s;
    for (auto ele : v) { s.insert(ele); }
    return s;
}
template <class T>
vector<T> SET_2_VECTOR(set<T>& s) {
    vector<T> v;
    for (auto ele : s) { v.push_back(ele); }
    return v;
}
#pragma endregion Basic
#pragma region overload
template <class T, class S>
void operator+=(vector<T>& l, S& r) {
    for (auto i : r) { l.push_back(i); }
}
template <class T, class S>
void operator+=(set<T>& l, S& r) {
    for (auto i : r) { l.insert(i); }
}
template <class T, class S>
void operator+=(multiset<T>& l, S& r) {
    for (auto i : r) { l.insert(i); }
}
template <class T, class S>
vector<T> operator+(vector<T>& l, S& r) {
    vector<T> l_copy = l;
    for (auto i : r) { l_copy.push_back(i); }
    return l_copy;
}
template <class T>
vector<T> operator+(const vector<T> l, const vector<T>& r) {
    vector<T> l_copy = l;
    for (auto i : r) { l_copy.push_back(i); }
    return l_copy;
}
template <class T, class S>
set<T> operator+(set<T>& l, S& r) {
    set<T> l_copy = l;
    for (auto i : r) { l_copy.insert(i); }
    return l_copy;
}
template <class T>
set<T> operator+(const set<T> l, const set<T>& r) {
    set<T> l_copy = l;
    for (auto i : r) { l_copy.insert(i); }
    return l_copy;
}
template <class T, class S>
multiset<T> operator+(multiset<T>& l, S& r) {
    set<T> l_copy = l;
    for (auto i : r) { l_copy.insert(i); }
    return l_copy;
}
template <class T>
multiset<T> operator+(const multiset<T> l, const set<T>& r) {
    set<T> l_copy = l;
    for (auto i : r) { l_copy.insert(i); }
    return l_copy;
}
string operator+(const string l, const string& r) {
    string str = l;
    str += r;
    return str;
}
string operator*(const string l, const size_t& r) {
    string str = l;
    for (size_t i = 0; i < r; i++) { str += l; }
    return str;
}
#pragma endregion overload
#pragma region Input
template <class Head>
void INPUT(vector<Head>& head);
template <size_t N, class Head>
void INPUT(array<Head, N>& head);
template <class T1>
void INPUT(tuple<T1>& t);
template <class T1, class T2>
void INPUT(tuple<T1, T2>& t);
template <class T1, class T2, class T3>
void INPUT(tuple<T1, T2, T3>& t);
template <class T1, class T2, class T3, class T4>
void INPUT(tuple<T1, T2, T3, T4>& t);
template <class T1, class T2, class T3, class T4, class T5>
void INPUT(tuple<T1, T2, T3, T4, T5>& t);
template <class Head>
void INPUT(Head& head);
template <class Head, class... Tail>
void INPUT(Head& head, Tail&... tail);
//本体
template <class Head>
void INPUT(vector<Head>& head) {
    for (size_t i = 0; i < head.size(); i++) { INPUT(head[i]); }
}
template <size_t N, class Head>
void INPUT(array<Head, N>& head) {
    for (size_t i = 0; i < head.size(); i++) { INPUT(head[i]); }
}
template <class T1>
void INPUT(tuple<T1>& t) {
    cin >> get<0>(t);
}
template <class T1, class T2>
void INPUT(tuple<T1, T2>& t) {
    cin >> get<0>(t) >> get<1>(t);
}
template <class T1, class T2, class T3>
void INPUT(tuple<T1, T2, T3>& t) {
    cin >> get<0>(t) >> get<1>(t) >> get<2>(t);
}
template <class T1, class T2, class T3, class T4>
void INPUT(tuple<T1, T2, T3, T4>& t) {
    cin >> get<0>(t) >> get<1>(t) >> get<2>(t) >> get<3>(t);
}
template <class T1, class T2, class T3, class T4, class T5>
void INPUT(tuple<T1, T2, T3, T4, T5>& t) {
    cin >> get<0>(t) >> get<1>(t) >> get<2>(t) >> get<3>(t) >> get<4>(t);
}
template <class Head>
void INPUT(Head& head) {
    cin >> head;
}
template <class Head, class... Tail>
void INPUT(Head& head, Tail&... tail) {
    INPUT(head);
    INPUT((tail)...);
}
#pragma endregion Input
#pragma region Print
template <class T1>
void PRINT2(tuple<T1> t);
template <class T1, class T2>
void PRINT2(tuple<T1, T2> t);
template <class T1, class T2, class T3>
void PRINT2(tuple<T1, T2, T3> t);
template <class T1, class T2, class T3, class T4>
void PRINT2(tuple<T1, T2, T3, T4> t);
template <class T1, class T2, class T3, class T4, class T5>
void PRINT2(tuple<T1, T2, T3, T4, T5> t);
template <class Head>
void PRINT2(vector<Head> head);
template <class Head>
void PRINT2(vector<vector<Head>> head);
template <size_t N, class Head>
void PRINT2(vector<array<Head, N>> head);
template <class... Head>
void PRINT2(vector<tuple<Head...>> head);
template <size_t N, class Head>
void PRINT2(array<Head, N> head);
template <class Head>
void PRINT2(Head head);
template <class Head, class... Tail>
void PRINT2(Head head, Tail... tail);
template <class Head>
void PRINT(Head head);
template <class... Head>
void PRINT(Head... head);
template <int N, class Head>
void PRINT(Head head);
template <class T1>
void PRINT2(tuple<T1> t) {
    PRINT2(get<0>(t));
}
template <class T1, class T2>
void PRINT2(tuple<T1, T2> t) {
    PRINT2(get<0>(t), get<1>(t));
}
template <class T1, class T2, class T3>
void PRINT2(tuple<T1, T2, T3> t) {
    PRINT2(get<0>(t), get<1>(t), get<2>(t));
}
template <class T1, class T2, class T3, class T4>
void PRINT2(tuple<T1, T2, T3, T4> t) {
    PRINT2(get<0>(t), get<1>(t), get<2>(t), get<3>(t));
}
template <class T1, class T2, class T3, class T4, class T5>
void PRINT2(tuple<T1, T2, T3, T4, T5> t) {
    PRINT2(get<0>(t), get<1>(t), get<2>(t), get<3>(t), get<4>(t));
}
template <class Head>
void PRINT2(vector<Head> head) {
    for (auto i = head.begin(); i != head.end(); i++) {
        PRINT2(*i);
        if (i != head.end() - 1) { cout << " "; }
    }
}
template <class Head>
void PRINT2(vector<vector<Head>> head) {
    for (auto i = head.begin(); i != head.end(); i++) {
        PRINT2(*i);
        if (i != head.end() - 1) { cout << endl; }
    }
}
template <size_t N, class Head>
void PRINT2(vector<array<Head, N>> head) {
    for (auto i = head.begin(); i != head.end(); i++) {
        PRINT2(*i);
        if (i != head.end() - 1) { cout << endl; }
    }
}
template <class... Head>
void PRINT2(vector<tuple<Head...>> head) {
    for (auto i = head.begin(); i != head.end(); i++) {
        PRINT2(*i);
        if (i != head.end() - 1) { cout << endl; }
    }
}
template <size_t N, class Head>
void PRINT2(array<Head, N> head) {
    for (auto i = head.begin(); i != head.end(); i++) {
        PRINT2(*i);
        if (i != head.end() - 1) { cout << " "; }
    }
}
template <class Head>
void PRINT2(Head head) {
    cout << head;
}
template <class Head, class... Tail>
void PRINT2(Head head, Tail... tail) {
    PRINT2(head);
    cout << " ";
    PRINT2((tail)...);
}
template <class Head>
void PRINT(Head head) {
    PRINT2(head);
    cout << endl;
}
template <class... Head>
void PRINT(Head... head) {
    PRINT2((head)...);
    cout << endl;
}
template <int N, class Head>
void PRINT(Head head) {
    PRINT2(head);
    cout << endl;
}
#pragma endregion Print
#pragma endregion Macro

struct weighted_unionfind {  // size:要素数,tree：unionfind木
    int n;
    vector<int> tree_root;
    vector<int> tree_depth;
    vector<int> tree_weight;

    weighted_unionfind(int temp) {
        n = temp;
        tree_root.assign(n, 0);
        tree_depth.assign(n, 1);
        tree_weight.assign(n, 0);
        for (int i = 0; i < n; i++) { tree_root[i] = i; }
    }

    // rootを探す
    tuple<int, int> root(int index) {
        vector<int> temp_list(0);
        int temp = tree_root[index];
        int dist = 0;
        while (index != temp) {
            temp_list.push_back(index);
            dist += tree_weight[index];
            index = temp;
            temp = tree_root[index];
        }
        int dist2 = dist;
        for (int i : temp_list) {
            tree_root[i] = index;
            temp = tree_weight[i];
            tree_weight[i] = dist2;
            dist2 -= temp;
        }
        return make_tuple(index, dist);
    }
    //結合
    void unite(int index1, int index2, int dist) {
        int r1, r2, k1, k2;
        tie(r1, k1) = root(index1);
        tie(r2, k2) = root(index2);
        if (r1 != r2) {
            int d1 = tree_depth[r1];
            int d2 = tree_depth[r2];
            if (d1 <= d2) {
                tree_root[r1] = r2;
                tree_weight[r1] = dist - k1 + k2;
                tree_depth[r2] = max(d1 + 1, d2);
            } else {
                tree_root[r2] = r1;
                tree_weight[r2] = -dist + k1 - k2;
                tree_depth[r1] = max(d2 + 1, d1);
            }
        }
    }
    //同じか判定
    tuple<bool, int> same(int index1, int index2) {
        int r1, r2, k1, k2;
        tie(r1, k1) = root(index1);
        tie(r2, k2) = root(index2);
        if (r1 == r2) {
            return make_tuple(true, k1 - k2);
        } else {
            return make_tuple(false, 0);
        }
    }
    //連結成分の個数
    int component() {
        set<int> s;
        for (int i : tree_root) { s.insert(i); }
        return (int)s.size();
    }
};

int main() {
    PRE_COMMAND
    int n, m;
    INPUT(n, m);
    weighted_unionfind u(n);
    for (int i = 0; i < m; i++) {
        int s, x, y, z;
        INPUT(s, x, y);
        if (s == 0) {
            INPUT(z);
            u.unite(x, y, z);
        } else {
            bool b;
            int ans;
            tie(b, ans) = u.same(x, y);
            if (b) {
                PRINT(ans);
            } else {
                PRINT("?");
            }
        }
    }
}


Measured memory_bytes: 3852