using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	static List<Tuple<int,int>>[] li;
	static bool[] b;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		int n=s[0],m=s[1];
		var t=sc.Ia;
		li=new List<Tuple<int,int>>[n+1];
		b=new bool[n+1];
		var c=new long[n+1];
		var d=new Mint[n+1];
		var f=new long[n+1];
		var g=new Mint[n+1];
		for(int i=1;i<=n;i++){
			li[i]=new List<Tuple<int,int>>();
			c[i]=long.MaxValue;
			f[i]=long.MaxValue;
		}
		for(int i=0;i<m;i++){
			var e=sc.Ia;
			li[e[0]].Add(Tuple.Create(e[1],e[2]));
			li[e[1]].Add(Tuple.Create(e[0],e[2]));
		}
		var pq=new Rheap<int>(32);
		pq.Push(new Rheap<int>.Dt(0,t[0]));
		c[t[0]]=0;
		d[t[0]]=1;
		while(pq.cnt>0){
			var e=pq.Dequeue;
			if(b[e.d]){continue;}
			b[e.d]=true;
			for(int i=0;i<li[e.d].Count;i++){
				if(!b[li[e.d][i].Item1]&&c[li[e.d][i].Item1]>li[e.d][i].Item2+e.n){
					pq.Push(new Rheap<int>.Dt(li[e.d][i].Item2+e.n,li[e.d][i].Item1));
					c[li[e.d][i].Item1]=li[e.d][i].Item2+e.n;
					d[li[e.d][i].Item1]=d[e.d];
				}
				else if(c[li[e.d][i].Item1]==li[e.d][i].Item2+e.n){
					d[li[e.d][i].Item1]+=d[e.d];
				}
			}
		}
		var u=(double)c[t[1]]/2;
		b=new bool[n+1];
		pq=new Rheap<int>(32);
		pq.Push(new Rheap<int>.Dt(0,t[1]));
		f[t[1]]=0;
		g[t[1]]=1;
		Mint ans=d[t[1]]*d[t[1]];
		while(pq.cnt>0){
			var e=pq.Dequeue;
			if(b[e.d]){continue;}
			b[e.d]=true;
			if(f[e.d]>=u){
				if(f[e.d]==u){
					ans-=g[e.d]*d[e.d]*g[e.d]*d[e.d];
				}
				continue;
			}
			for(int i=0;i<li[e.d].Count;i++){
				if(!b[li[e.d][i].Item1]&&f[li[e.d][i].Item1]>li[e.d][i].Item2+e.n){
					pq.Push(new Rheap<int>.Dt(li[e.d][i].Item2+e.n,li[e.d][i].Item1));
					f[li[e.d][i].Item1]=li[e.d][i].Item2+e.n;
					g[li[e.d][i].Item1]=g[e.d];
				}
				else if(f[li[e.d][i].Item1]==li[e.d][i].Item2+e.n){
					g[li[e.d][i].Item1]+=g[e.d];
				}
				if(f[e.d]+li[e.d][i].Item2+c[li[e.d][i].Item1]==c[t[1]]&&li[e.d][i].Item2+e.n>u){
					ans-=g[e.d]*d[li[e.d][i].Item1]*g[e.d]*d[li[e.d][i].Item1];
				}
			}
		}
		Console.WriteLine("{0}",ans);
	}
	static void Fu(int a,int g){
		b[a]=true;
		for(int i=0;i<li[a].Count;i++){
			if(!b[li[a][i].Item1]){Fu(li[a][i].Item1,g);}
		}
	}
}
public struct Mint{
	const int mod=(int)1e9+7;
	private long d;
	public Mint(long d){this.d=d;}
	public static implicit operator Mint(long d){return new Mint(d%mod);}
	public static explicit operator long(Mint d){return d.d;}
	public override string ToString(){return d.ToString();}
	public static Mint operator+(Mint a,long b){a.d=(a.d+b)%mod;return a;}
	public static Mint operator+(Mint a,Mint b){a.d=(a.d+b.d)%mod;return a;}
	public static Mint operator-(Mint a,long b){a.d=(mod+a.d-b)%mod;return a;}
	public static Mint operator-(Mint a,Mint b){a.d=(mod+a.d-b.d)%mod;return a;}
	public static Mint operator*(Mint a,long b){a.d=(a.d*b)%mod;return a;}
	public static Mint operator*(Mint a,Mint b){a.d=(a.d*b.d)%mod;return a;}
	public static Mint operator/(Mint a,long b){a.d=(a.d*Mi(b))%mod;return a;}
	public static Mint operator/(Mint a,Mint b){a.d=(a.d*Mi(b.d))%mod;return a;}
	private static long Mi(long a){
		a=(a+mod)%mod;
		long b=mod,u=1,v=0;
		while(b>0){
			long t=a/b;
			a-=t*b;a^=b;b^=a;a^=b;
			u-=t*v;u^=v;v^=u;u^=v;
		}
		u%=mod;
		if(u<0){u+=mod;}
		return u%mod;
	}
}
public class Rheap<T>{
	public class Dt{
		public long n;
		public T d;
		public Dt(long n,T d){this.n=n;this.d=d;}
	}
	private const int m=65;
	private long la=0;
	private Dt[][] bf;
	private int[] h;
	public int cnt=0;
	public Rheap(int max){
		bf=new Dt[m][];
		h=new int[m];
		for(int i = 0;i<m;i++) {bf[i]=new Dt[max];}
	}
	public void Push(Dt x){
		int a=x.n!=la?Bsr(la^x.n)+1:0;
		if(h[a]==bf[a].Length){Extend(a);}
		bf[a][h[a]]=x;
		cnt++;
		h[a]++;
	}
	public Dt Peek{get{
		if(h[0]==0){
			for(int i = 1;i<m;i++) {
				if(h[i]>0){
					int p=0;
					for(int j = 1;j<h[i];j++) {
						if(bf[i][p].n>bf[i][j].n){p=j;}
					}
					la=bf[i][p].n;
					for(int j = 0;j<h[i];j++) {
						Push(bf[i][j]);
						cnt--;
					}
					h[i]=0;
					break;
				}
			}
		}
		return bf[0][h[0]-1];
	}}
	public Dt Dequeue{get{
		var e=Peek;
		h[0]--;
		cnt--;
		return e;
	}}
	private void Extend(int n){
		var nhe=new Dt[bf[n].Length<<1];
		Array.Copy(bf[n],nhe,bf[n].Length);
		bf[n]=nhe;
	}
	private int Bsr(long b){
		int n=0;
		if(b==0){return -1;}
		if((b&-4294967296)!=0){b=b&-4294967296;n+=32;}
		if((b&-281470681808896)!=0){b=b&-281470681808896;n+=16;}
		if((b&-71777214294589696)!=0){b=b&-71777214294589696;n+=8;}
		if((b&-1085102592571150096)!=0){b=b&-1085102592571150096;n+=4;}
		if((b&-3689348814741910324)!=0){b=b&-3689348814741910324;n+=2;}
		if((b&-6148914691236517206)!=0){b=b&-6148914691236517206;n+=1;}
		return n;
	}
}

public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),int.Parse);}
	public int[] Ia3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(int a){return Array.ConvertAll((a.ToString()+" "+Console.ReadLine()).Split(),long.Parse);}
	public long[] La3(bool a,int b,bool c,int d){return Array.ConvertAll(((a?b.ToString()+" ":"")+Console.ReadLine()+(c?" "+d.ToString():"")).Split(),long.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}

Measured memory_bytes: 53168