#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a) {
    out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
    out<<'[';
    for(const T &i: a) out<<i<<',';
    out<<']';
    return out;
}
template<class T>
ostream &operator <<(ostream& out, const set<T>& a) {
    out<<'{';
    for(const T &i: a) out<<i<<',';
    out<<'}';
    return out;
}
template<class T, class S>
ostream &operator <<(ostream& out, const map<T,S>& a) {
    out<<'{';
    for(auto &i: a) out<<i<<',';
    out<<'}';
    return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll n, m;
    cin >> n >> m;
    vector<vector<PII>> g(n);
    REP(i, m) {
        ll u, v, w;
        cin >> u >> v >> w;
        u--, v--;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }

    vector<bool> used(n);
    vector<vector<ll>> a(n, vector<ll>(2));
    function<void(int)> dfs = [&](int v) {
        used[v] = true;
        for(auto e: g[v]) {
            if(used[e.first]) continue;
            a[e.first][0] = -a[v][0];
            a[e.first][1] = e.second - a[v][1];
            dfs(e.first);
        }
    };
    a[0][0] = 1;
    dfs(0);

    ll l = 1, r = LLINF, f = -1;
    REP(i, n) {
        if(a[i][0] == 1) chmax(l, 1-a[i][1]);
        else chmin(r, a[i][1] - 1);
        for(auto e: g[i]) {
            ll u = e.first;
            ll x = a[i][0] + a[u][0], y = a[i][1] + a[u][1];
            if(x == 0) {
                if(y != e.second) {
                    cout << 0 << endl;
                    return 0;
                }
            } else {
                ll z = e.second - y;
                if(z%2 != 0) {
                    cout << 0 << endl;
                    return 0;
                }
                z /= x;
                if(z <= 0) {
                    cout << 0 << endl;
                    return 0;
                }
                if(f == -1) f = z;
                if(f != z) {
                    cout << 0 << endl;
                    return 0;
                }
            }
        }
    }

    if(f == -1) {
        cout << max(0LL, r-l+1) << endl;
    } else {
        if(l <= f && f <= r) cout << 1 << endl;
        else cout << 0 << endl;
    }

    return 0;
}


Measured memory_bytes: 19200