#include <bits/stdc++.h>
using namespace std;


#define li          long long int
#define rep(i,to)   for(li i=0;i<((li)(to));i++)
#define repp(i,start,to)    for(li i=(li)(start);i<((li)(to));i++)
#define pb          push_back
#define sz(v)       ((li)(v).size())
#define bgn(v)      ((v).begin())
#define eend(v)     ((v).end())
#define allof(v)    (v).begin(), (v).end()
#define dodp(v,n)       memset(v,(li)n,sizeof(v))
#define bit(n)      (1ll<<(li)(n))
#define mp(a,b)     make_pair(a,b)
#define rin rep(i,n)
#define EPS 1e-12
#define ETOL 1e-8
#define MOD 1000000007
typedef pair<li, li> PI;

#define INF bit(60)

#define DBGP 1


#define idp if(DBGP)
#define F first
#define S second
#define p2(a,b)     idp cout<<a<<"\t"<<b<<endl
#define p3(a,b,c)       idp cout<<a<<"\t"<<b<<"\t"<<c<<endl
#define p4(a,b,c,d)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<endl
#define p5(a,b,c,d,e)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<endl
#define p6(a,b,c,d,e,f)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<endl
#define p7(a,b,c,d,e,f,g)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<endl
#define p8(a,b,c,d,e,f,g,h)     idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<endl
#define p9(a,b,c,d,e,f,g,h,i)       idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<endl
#define p10(a,b,c,d,e,f,g,h,i,j)        idp cout<<a<<"\t"<<b<<"\t"<<c<<"\t"<<d<<"\t"<<e<<"\t"<<f<<"\t"<<g<<"\t"<<h<<"\t"<<i<<"\t"<<j<<endl
#define foreach(it,v)   for(__typeof((v).begin()) it=(v).begin(); it!=(v).end(); ++it)
#define p2p(x)      idp p2((x).F, (x).S)
#define dump(x,n)   idp{rep(i,n){cout<<x[i]<<" ";}puts("");}
#define dump2(x,n)  idp{rep(i,n){cout<<"["<<x[i].F<<" , "<<x[i].S<<"] ";}puts("");}
#define dumpi(x)    idp{foreach(it, x){cout<<(*it)<<" ";}puts("");}
#define dumpi2(x)   idp{foreach(it, x){cout<<"["<<(it)->F<<" , "<<(it)->S<<"] ";}puts("");}

#define read2d(a,w,h)   rep(i,h)rep(j,w)cin>>a[i][j]
#define dump2d(a,w,h)   rep(i,h){rep(j,w)cout<<a[i][j]<<" ";puts("");}

typedef pair<li, li> PI;

li n, m;
vector<PI> edge[100100];

PI d0[100100];

li chk_[100100];

li checkOddLoop(li from, li now) {
    rep(i, sz(edge[now])) {
        li next = edge[now][i].F;
        if (next == from) {
            continue;
        }
        PI next_d = { -1 * d0[now].F, edge[now][i].S - d0[now].S};
        if (d0[next].S != -INF) {
            if (d0[next].F == next_d.F) {
                if (d0[next].S != next_d.S) {
                    return -INF;
                }
                continue;
            } else {
                li t2;
                if (d0[next].F == 1) {
                    t2 = next_d.S - d0[next].S;
                } else {
                    t2 = d0[next].S - next_d.S;
                }

                if (t2 <= 0 || t2 % 2 != 0) {
                    return -INF;
                }
                return t2 / 2;
            }
        }
        d0[next] = next_d;
        li dfs_res = checkOddLoop(now, next);
        if (dfs_res != -1) {
            return dfs_res;
        }
    }
    return -1;
}

bool chk(li val) {
    rep(i, n) {
        chk_[i] = -1;
    }
    stack<PI> stk;
    stk.push({0, val});
    while (!stk.empty()) {
        li now = stk.top().F;
        li now_val = stk.top().S;
        stk.pop();
        if (now_val <= 0) {
            return false;
        }
        if (chk_[now] != -1) {
            if (chk_[now] != now_val) {
                return false;
            }
            continue;
        }
        chk_[now] = now_val;
        rep(i, sz(edge[now])) {
            li next = edge[now][i].F;
            stk.push({next, edge[now][i].S - now_val});
        }
    }
    return true;
}

bool dfs(li from, li now) {
    return true;
}

int main() {
    cin >> n >> m;
    rep(i, m) {
        li u, v, s;
        cin >> u >> v >> s;
        u--;
        v--;
        edge[u].pb({v, s});
        edge[v].pb({u, s});
    }

    rin{d0[i].S = -INF;}

    d0[0].F = 1;
    d0[0].S = 0;

    li tres = checkOddLoop(-1, 0);
    if (tres == -INF) {
        puts("0");
        return 0;
    } else if (tres != -1) {
        if (chk(tres)) {
            puts("1");
        } else {
            puts("0");
        }
        return 0;
    }

    // no odd loop
    li min_d0[2];
    min_d0[0] = 0;
    min_d0[1] = INF;
    rin{
        if (d0[i].F == 1) {
            min_d0[0] = min(min_d0[0], d0[i].S);
        } else{
            min_d0[1] = min(min_d0[1], d0[i].S);
        }
    }
    li minn = 1 - min_d0[0];
    li maxx = min_d0[1] - 1;
    if (minn > maxx) {
        puts("0");
    } else {
        cout << maxx - minn + 1 << endl;
    }
    return 0;
}

Measured memory_bytes: 14080