use std::collections::{BinaryHeap, VecDeque};

const INF: i64 = 1 << 50;
const MOD: usize = 1e9 as usize + 7;
fn main() {
    let (r, w) = (std::io::stdin(), std::io::stdout());
    let mut sc = IO::new(r.lock(), w.lock());

    let n: usize = sc.read();
    let m: usize = sc.read();
    let s = sc.read::<usize>() - 1;
    let t = sc.read::<usize>() - 1;
    let mut graph = vec![vec![]; n];
    for _ in 0..m {
        let a = sc.read::<usize>() - 1;
        let b = sc.read::<usize>() - 1;
        let cost: i64 = sc.read();
        graph[a].push((b, cost));
        graph[b].push((a, cost));
    }

    let (dist_s, count_s) = calc(s, &graph);
    let (dist_t, count_t) = calc(t, &graph);
    let distance = dist_s[t];

    let mut collision = 0;
    for a in 0..n {
        for &(b, cost) in graph[a].iter() {
            if dist_s[a] * 2 < distance
                && distance < dist_s[b] * 2
                && dist_s[a] + cost == dist_s[b]
                && dist_s[a] + dist_t[b] + cost == distance
            {
                let c = (count_s[a] * count_t[b]) % MOD;
                collision = (collision + c * c) % MOD;
            }
        }
    }

    for i in 0..n {
        if dist_s[i] * 2 == distance && dist_t[i] * 2 == distance {
            let c = (count_s[i] * count_t[i]) % MOD;
            collision = (collision + c * c) % MOD;
        }
    }

    let all = (count_s[t] * count_t[s]) % MOD;
    let ans = (all + MOD - collision) % MOD;
    println!("{}", ans);

    //    eprintln!("all={} collision={}", all, collision);
    //    eprintln!("{:?} {:?}", dist_s, count_s);
    //    eprintln!("{:?} {:?}", dist_t, count_t);
}

fn calc(s: usize, graph: &Vec<Vec<(usize, i64)>>) -> (Vec<i64>, Vec<usize>) {
    let n = graph.len();
    let dist = dijkstra(s, graph);
    let mut lower_count = vec![0; n];
    for from in 0..n {
        for &(next, cost) in graph[from].iter() {
            if dist[from] + cost == dist[next] {
                lower_count[next] += 1;
            }
        }
    }

    let mut reached: Vec<usize> = vec![0; n];
    let mut comb = vec![0; n];
    comb[s] = 1;
    let mut q = VecDeque::new();
    q.push_back(s);
    while let Some(v) = q.pop_front() {
        for &(next, cost) in graph[v].iter() {
            if dist[v] + cost == dist[next] {
                comb[next] += comb[v];
                comb[next] %= MOD;
                //                eprintln!("s={} {} => {}", s + 1, v + 1, next + 1);

                reached[next] += 1;
                if reached[next] == lower_count[next] {
                    q.push_back(next);
                }
            }
        }
    }
    (dist, comb)
}

fn dijkstra(start: usize, graph: &Vec<Vec<(usize, i64)>>) -> Vec<i64> {
    let n = graph.len();
    let mut dist = vec![INF; n];
    dist[start] = 0;

    let mut heap = BinaryHeap::new();
    heap.push((0, start));
    while let Some((_, v)) = heap.pop() {
        for &(next, cost) in graph[v].iter() {
            if dist[next] > dist[v] + cost {
                dist[next] = dist[v] + cost;
                heap.push((-dist[next], next));
            }
        }
    }
    dist
}

pub struct IO<R, W: std::io::Write>(R, std::io::BufWriter<W>);

impl<R: std::io::Read, W: std::io::Write> IO<R, W> {
    pub fn new(r: R, w: W) -> IO<R, W> {
        IO(r, std::io::BufWriter::new(w))
    }
    pub fn write<S: std::ops::Deref<Target = str>>(&mut self, s: S) {
        use std::io::Write;
        self.1.write(s.as_bytes()).unwrap();
    }
    pub fn read<T: std::str::FromStr>(&mut self) -> T {
        use std::io::Read;
        let buf = self
            .0
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b' ' || b == b'\n' || b == b'\r' || b == b'\t')
            .take_while(|&b| b != b' ' && b != b'\n' && b != b'\r' && b != b'\t')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn vec<T: std::str::FromStr>(&mut self, n: usize) -> Vec<T> {
        (0..n).map(|_| self.read()).collect()
    }
    pub fn chars(&mut self) -> Vec<char> {
        self.read::<String>().chars().collect()
    }
}


Measured memory_bytes: 25600