using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
using System.Numerics;
using static Template;
using static System.Console;
using static System.Convert;
using static System.Math;
using Pi = Pair<int, int>;

class Solver
{

    public void Solve(Scanner sc)
    {
        int N, Q;
        sc.Make(out N, out Q);
        var uf = new WeightedUnionFind(N);
        while (Q-- > 0)
        {
            var t = sc.Next<int>();
            if (t == 0)
            {
                int x, y, z;
                sc.Make(out x, out y, out z);
                uf.Union(x, y, z);
            }
            else
            {
                int x, y;sc.Make(out x, out y);
                if (uf[x] != uf[y]) WriteLine("?");
                else WriteLine(uf.Dif(x, y));
            }
        }
    }
}

class WeightedUnionFind
{
    public int GroupCount { get; private set; }
    protected int[] data;
    private long[] dif;
    public virtual int this[int i] { get { return Find(i); } }
    public WeightedUnionFind(int size)
    {
        data = new int[size]; dif = new long[size];
        GroupCount = size;
        for (var i = 0; i < size; i++)
            data[i] = -1;
    }
    protected int Find(int i)
    {
        if (data[i] < 0) return i;
        var root = Find(data[i]);
        dif[i] += dif[data[i]];
        return data[i] = root;
    }
    private long Weight(int i) { Find(i); return dif[i]; }
    public long Dif(int u, int v)
        => Weight(v) - Weight(u);
    public int Size(int i)
        => -data[Find(i)];
    public virtual bool Union(int u, int v, long w)
    {
        w += Weight(u); w -= Weight(v);
        u = Find(u); v = Find(v);
        if (u == v) return false;
        if (data[u] > data[v])
        { swap(ref u, ref v); w = -w; }
        GroupCount--;
        data[u] += data[v];
        data[v] = u;
        dif[v] = w;
        return true;
    }
}


public class RollingHash
{
    public string str { get; }
    private ulong[] hashTable;
    private static ulong[] pow;
    private static uint Base { get; }
    const ulong MASK30 = (1UL << 30) - 1;
    const ulong MASK31 = (1UL << 31) - 1;
    private const ulong MOD = (1UL << 61) - 1;
    public RollingHash(string str)
    {
        this.str = str;
        hashTable = new ulong[str.Length + 1];
        for (var j = 1; j <= str.Length; j++)
            hashTable[j] = CalcMod(Mul(hashTable[j - 1], Base) + str[j - 1]);
    }
    static RollingHash()
    {
        var rnd = new Random(); int min = 150, max = int.MaxValue;
        Base = (uint)rnd.Next(min, max);
        pow = new ulong[31];
        pow[0] = 1;
        for (var j = 1; j < pow.Length; j++)
            pow[j] = Mul(pow[j - 1], Base);
    }

    private static ulong Mul(ulong a, ulong b)
    {
        var au = a >> 31;
        var ad = a & MASK31;
        var bu = b >> 31;
        var bd = b & MASK31;
        var mid = ad * bu + au * bd;
        var midu = mid >> 30;
        var midd = (mid & MASK30);
        return CalcMod(au * bu * 2 + midu + (midd << 31) + ad * bd);
    }
    private static ulong CalcMod(ulong val)
    {
        val = (val & MOD) + (val >> 61);
        if (val > MOD) val -= MOD;
        return val;
    }

    public ulong GetHash(int l = 0, int r = -1)
    {
        if (r < 0) r = str.Length;
        return CalcMod(hashTable[r] + MOD * ((1UL << 3) - 1) - Mul(hashTable[l], pow[r - l]));
    }
}
#region Template
public static class Template
{
    static void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver().Solve(new Scanner());
        Console.Out.Flush();
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) == 1) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) == -1) { a = b; return true; } return false; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void swap<T>(ref T a, ref T b) { var t = b; b = a; a = t; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(); return rt; }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static T[] Create<T>(int n, Func<int, T> f) { var rt = new T[n]; for (var i = 0; i < rt.Length; ++i) rt[i] = f(i); return rt; }
    public static T Unify<T>(this T[] A, Func<T, T, T> f, T init = default(T)) { for (var i = 0; i < A.Length; i++) init = f(init, A[i]); return init; }
    public static void Fail<T>(T s) { Console.WriteLine(s); Console.Out.Close(); Environment.Exit(0); }
}

public class Scanner
{
    public string Str => Console.ReadLine().Trim();
    public int Int => int.Parse(Str);
    public long Long => long.Parse(Str);
    public double Double => double.Parse(Str);
    public int[] ArrInt => Str.Split(' ').Select(int.Parse).ToArray();
    public long[] ArrLong => Str.Split(' ').Select(long.Parse).ToArray();
    public char[][] Grid(int n) => Create(n, () => Str.ToCharArray());
    public int[] ArrInt1D(int n) => Create(n, () => Int);
    public long[] ArrLong1D(int n) => Create(n, () => Long);
    public int[][] ArrInt2D(int n) => Create(n, () => ArrInt);
    public long[][] ArrLong2D(int n) => Create(n, () => ArrLong);
    private Queue<string> q = new Queue<string>();
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public T Next<T>() { if (q.Count == 0) foreach (var item in Str.Split(' ')) q.Enqueue(item); return (T)Convert.ChangeType(q.Dequeue(), typeof(T)); }
    public void Make<T1>(out T1 v1) => v1 = Next<T1>();
    public void Make<T1, T2>(out T1 v1, out T2 v2) { v1 = Next<T1>(); v2 = Next<T2>(); }
    public void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3) { Make(out v1, out v2); v3 = Next<T3>(); }
    public void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4) { Make(out v1, out v2, out v3); v4 = Next<T4>(); }
    public void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5) { Make(out v1, out v2, out v3, out v4); v5 = Next<T5>(); }
    public void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6) { Make(out v1, out v2, out v3, out v4, out v5); v6 = Next<T6>(); }
    //public (T1, T2) Make<T1, T2>() { Make(out T1 v1, out T2 v2); return (v1, v2); }
    //public (T1, T2, T3) Make<T1, T2, T3>() { Make(out T1 v1, out T2 v2, out T3 v3); return (v1, v2, v3); }
    //public (T1, T2, T3, T4) Make<T1, T2, T3, T4>() { Make(out T1 v1, out T2 v2, out T3 v3, out T4 v4); return (v1, v2, v3, v4); }
}
public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1;
    public T2 v2;
    public Pair() { }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString() => $"{v1.ToString()} {v2.ToString()}";
    public void Deconstruct(out T1 a, out T2 b) { a = v1; b = v2; }
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3;
    public Pair() : base() { }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString() => $"{base.ToString()} {v3.ToString()}";
    public void Deconstruct(out T1 a, out T2 b, out T3 c) { Deconstruct(out a, out b); c = v3; }
}
#endregion


Measured memory_bytes: 23384