/**
 *    author:  otera    
**/
#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<deque>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
using namespace std;

typedef long long ll;
typedef unsigned long long ul;
typedef unsigned int ui;
typedef long double ld;
const int inf=1e9+7;
const ll INF=1LL<<60 ;
const ll mod=1e9+7 ;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<int, int> P;
typedef pair<ld, ld> LDP;
typedef pair<ll, ll> LP;
#define fr first
#define sc second
#define all(c) c.begin(),c.end()
#define pb push_back
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
#define int long long

struct edge {int to, cost; };

int n, m;
vector<vector<edge>> g;
int t;
int check;

// bool vis[100100][2];
// int number[100100][2];
vector<int> color;
vector<int> number;

void dfs(int v, int c, int num) {
    if(color[v] == -1) {
        color[v] = c; //探索し終わった目標をつけておく
        number[v] = num;
    } else {
        if(color[v] == c) {
            if(number[v] != num) {
                cout << 0 << endl;
                exit(0);
            } 
        } else {
            int a = number[v] - num;
            if(a % 2 == 1) {
                cout << 0 << endl;
                exit(0);
            } else {
                int u;
                if(c == 1) {
                    u = (num - number[v]) / 2;
                } else {
                    u = (number[v] - num) / 2;
                }

                if(check == 1 && u != t) {
                    cout << 0 << endl;
                    exit(0);
                }
                if(check == 2) {
                    t = u;
                    check = 1;
                }
            }
        }
        return; //もうすでに探索した　//ループになってる
    }
    for(auto nv: g[v]) {
        dfs(nv.to, 1 ^ c, nv.cost - num);
    }
}

void solve() {
	cin >> n >> m;
    g.assign(n, vector<edge>());
    color.assign(n, -1);
    number.resize(n);
    check = 2;
    rep(i, m) {
        int u, v, s; cin >> u >> v >> s;
        --u; --v;
        g[u].pb(edge{v, s});
        g[v].pb(edge{u, s});
    }
    dfs(0, 0, 0);
    if(check == 1) {
        if(t > 0) {
            rep(i, n) {
                if(color[i] == 0) {
                    if(number[i] + t <= 0) {
                        cout << 0 << endl;
                        return;
                    }
                } else {
                    if(number[i] - t <= 0) {
                        cout << 0 << endl;
                        return;
                    }
                }
            }
            cout << 1 << endl;
        } else {
            cout << 0 << endl;
        }
        return;
    }
    int ma = INF, mi = -INF;
    rep(i, n) {
        if(color[i] == 0) {
            chmax(mi, 1 - number[i]);
        } else {
            chmin(ma, number[i] - 1);
        }
        cerr << number[i] << endl;
    }
    if(ma < mi) {
        cout << 0 << endl;
    } else {
        cout << ma - mi + 1 << endl;
    }
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//int t; cin >> t; rep(i, t)solve();
	solve();
    return 0;
}

Measured memory_bytes: 14080