// https://atcoder.jp/contests/soundhound2018-summer-qual/tasks/soundhound2018_summer_qual_e
//
#![allow(unused_imports)]
use std::io::*;
use std::io::Write;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

// Input macros.
// Original by tanakh: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };

    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, [ next / $t:tt ]) => {
        {
            let len = read_value!($iter, usize);
            (0..len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        }
    };

    ($iter:expr, switch) => {
        {
            let ty = read_value!($iter, i32);
            if ty == 1 {
                vec![ty, read_value!($iter, i32), read_value!($iter, i32)]
            } else if ty == 2 {
                vec![ty, read_value!($iter, i32)]
            } else {
                vec![ty, read_value!($iter, i32)]
            }
        }
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! read_line {
    ($t:tt) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).unwrap();
            s.trim_right().parse::<$t>().unwrap()
        }
    }
}

#[allow(unused_macros)]
macro_rules! dvec {
    ($t:expr ; $len:expr) => {
        vec![$t; $len]
    };

    ($t:expr ; $len:expr, $($rest:expr),*) => {
        vec![dvec!($t; $($rest),*); $len]
    };
}

#[allow(unused_macros)]
macro_rules! ifv {
    ($t:expr, $a:expr, $b: expr) => {
        if $t { $a } else { $b }
    }
}

#[allow(unused_macros)]
macro_rules! fill {
    ($t:expr, $v:expr) => {
        for i in 0..$t.len() {
            $t[i] = $v;
        }
    };
}

#[allow(unused_macros)]
macro_rules! join {
    ($t:expr, $glue:expr) => {
        $t.into_iter().map(|w| w.to_string()).collect::<Vec<_>>().join($glue)
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

// ===

fn dfs(now: usize, par: Option<usize>, g: &Vec<Vec<(usize, i64)>>, visited: &mut Vec<bool>, number: (i64, i64), history: &mut Vec<Vec<(i64, i64)>>) {
    history[now].push(number);
    if visited[now] {
        return;
    }
    visited[now] = true;

    for &(to, len) in &g[now] {
        if Some(to) == par {
            continue;
        }
        dfs(to, Some(now), g, visited, (-number.0, len-number.1), history);
    }
}

fn main() {
    input! {
        n: usize, m: usize,
        edges: [(usize1, usize1, i64); m]
    };

    let mut g = vec![vec![]; n];
    for (u, v, len) in edges {
        g[u].push((v, len));
        g[v].push((u, len));
    }

    let mut history = vec![vec![]; n];
    dfs(0, None, &g, &mut vec![false; n], (1, 0), &mut history);

    let mut valid = true;
    let mut minx = 0;
    let mut maxx = 1e12 as i64;
    for i in 0..n {
        let hn = history[i].len();
        for &(a, b) in &history[i] {
            if a == 1 {
                minx = max(minx, -b+1);
            } else {
                maxx = min(maxx, b-1);
            }
        }
        for j in 1..hn {
            if history[i][0].0 == history[i][j].0 {
                valid &= history[i][0] == history[i][j];
            } else {
                let diff = history[i][j].1 - history[i][0].1;
                if diff % 2 != 0 {
                    valid = false;
                }
                let uv = diff / (history[i][0].0 - history[i][j].0);
                minx = max(minx, uv);
                maxx = min(maxx, uv);
            }
        }
    }
    valid &= maxx-minx+1 >= 1;

    println!("{}", ifv!(valid, maxx-minx+1, 0));
}


Measured memory_bytes: 41332