#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define dupli(a) a.erase(unique(all(a)),a.end())
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const int INF=1001001001;
const int mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){a%=mod;if(b==0)return 1;if(b&1)return a*modpow(a,b-1)%mod;ll k=modpow(a,b/2);return k*k%mod;}
vvp g;
vp v;
ll t=inf;
bool ok=true;
void dfs(int i,int p){
    for(auto x:g[i])if(x.fi!=p){
        if(v[x.fi].fi==0){
            v[x.fi]=P(-v[i].fi,x.se-v[i].se);
            dfs(x.fi,i);
        }
        else{
            P k=P(-v[i].fi,x.se-v[i].se);
            if(v[x.fi]!=k){
                if(k.fi==v[x.fi].fi)ok=false;
                else{
                    ll tt=(v[x.fi].se-k.se)/(k.fi-v[x.fi].fi);
                    if(t==inf)t=tt;
                    else if(t!=tt)ok=false;
                }
            }
        }
    }
}
int main(){
    ll n,m;cin>>n>>m;
    g=vvp(n);
    rep(i,m){
        ll a,b,c;cin>>a>>b>>c;
        a--;b--;
        g[a].pb(b,c);
        g[b].pb(a,c);
    }
    v=vp(n,P(0,0));
    v[0]=P(1,0);
    dfs(0,-1);
    if(!ok)dame(0);
    vi a,b;
    rep(i,n){
        if(v[i].fi==1)a.pb(v[i].se);
        else b.pb(v[i].se);
    }
    ll mi=1,ma=inf;
    for(ll x:a)chmax(mi,-x+1);
    for(ll x:b)chmin(ma,x-1);
    if(mi>ma)dame(0);
    if(t==inf)dame(ma-mi+1);
    if(mi<=t&&t<=ma)dame(1);
    out(0);
}

Measured memory_bytes: 15616