#include <iostream>
#include <string>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <unordered_map>
#include <map>
#include <set>
#include <algorithm>
#include <queue>
#include <stack>
#include <functional>
#include <bitset>
#include <assert.h>
#include <unordered_map>
#include <fstream>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef pair<ll,ll> P;
typedef pair<int,int> pii;
typedef vector<P> vpl;
typedef tuple<ll,ll,ll> tapu;
#define rep(i,n) for(int i=0; i<(n); i++)
#define REP(i,a,b) for(int i=(a); i<(b); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int inf = 1<<30;
const ll linf = 1LL<<62;
const int MAX = 510000;
ll dy[8] = {1,-1,0,0,1,-1,1,-1};
ll dx[8] = {0,0,1,-1,1,-1,-1,1};
const double pi = acos(-1);
const double eps = 1e-7;
template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){
	if(a>b){
		a = b; return true;
	}
	else return false;
}
template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){
	if(a<b){
		a = b; return true;
	}
	else return false;
}
template<typename T> inline void print(T &a){
    rep(i,a.size()) cout << a[i] << " ";
    cout << "\n";
}
template<typename T1,typename T2> inline void print2(T1 a, T2 b){cout << a << " " << b << "\n";}
template<typename T1,typename T2,typename T3> inline void print3(T1 a, T2 b, T3 c){
	cout << a << " " << b << " " << c << "\n";
}
const int mod = 1e9 + 7;
//const int mod = 998244353;

template <std::uint_fast64_t Modulus> class modint {
  using u64 = std::uint_fast64_t;

public:
  u64 a;

  constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
  constexpr u64 &value() noexcept { return a; }
  constexpr const u64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
	return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
	return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
	return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
	return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
	a += rhs.a;
	if (a >= Modulus) {
	  a -= Modulus;
	}
	return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
	if (a < rhs.a) {
	  a += Modulus;
	}
	a -= rhs.a;
	return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
	a = a * rhs.a % Modulus;
	return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
	u64 exp = Modulus - 2;
	while (exp) {
	  if (exp % 2) {
		*this *= rhs;
	  }
	  rhs *= rhs;
	  exp /= 2;
	}
	return *this;
  }
};

using mint = modint<mod>;

vector<vpl> G(101010);
int n,m;

vector<pair<ll,mint>> dijkstra(int s){
	vector<pair<ll,mint>> d(n,{linf,0});
	d[s] = {0,1};
	priority_queue<P,vector<P>,greater<P>> pq;
	pq.emplace(0,s);
	while(!pq.empty()){
		auto p = pq.top(); pq.pop();
		ll u = p.second;
		if(d[u].first < p.first) continue;
		for(auto v : G[u]){
			ll nxt = d[u].first + v.second;
			if(d[v.first].first > nxt){
				d[v.first].first = nxt;
				d[v.first].second = d[u].second;
				pq.emplace(nxt,v.first);
			}else if(d[v.first].first == nxt){
				d[v.first].second += d[u].second;
			}
		}
	}
	return d;
}

int main(){
	cin >> n >> m;
	int s,t; cin >> s >> t; s--; t--;
	vector<tapu> edges(m);
	rep(i,m){
		ll u,v,d; scanf("%lld%lld%lld",&u,&v,&d); u--; v--;
		G[u].emplace_back(v,d);
		G[v].emplace_back(u,d);
		edges[i] = {u,v,d};
	}
	auto d = dijkstra(s);
	auto rd = dijkstra(t);
	mint ans = d[t].second * rd[s].second;
	rep(i,n){
		if(d[i].first == rd[i].first && d[i].first + rd[i].first == d[t].first){
			mint tmp = d[i].second * rd[i].second;
			ans -= tmp * tmp;
		}
	}
	rep(i,m){
		ll u,v,D;
		tie(u,v,D) = edges[i];
		if(d[u].first > d[v].first) swap(u,v);
		if(2*d[u].first < d[t].first && 2*d[v].first > d[t].first){
			if(d[u].first + D + rd[v].first == d[t].first){
				mint tmp = d[u].second * rd[v].second;
				ans -= tmp * tmp;
			}
		}
	}
	cout << ans.value() << "\n";
}


Measured memory_bytes: 26400