#include<bits/stdc++.h>
#define int long long
#define M 200005
#define N 100005
#define pii pair<int,double>
using namespace std;
priority_queue<int>q;
int n,m,s,vis[N],cnt;
double head[N],dis[N];
struct node
{
	int v,nxt;
	double w;
}e[M*2];
void edge(int u,int v,double w)
{
	e[++cnt].v=v;
	e[cnt].w=w;
	e[cnt].nxt=head[u];
	head[u]=cnt;
}
void dij(int s)
{
	q.push(s);
	dis[s]=1;
	while(!q.empty())
	{                                                             
		int u=q.top();
		q.pop();
		if(vis[u])continue;
		vis[u]=1;
		for(int i=head[u];i;i=e[i].nxt)
		{
			int vv=e[i].v;
			double ww=e[i].w;
			if(dis[vv]<dis[u]*ww)
			{
				dis[vv]=dis[u]*ww;
				q.push(vv);
			}
		}
	}
}
signed main()
{
	cin>>n>>m;
	for(int i=1;i<=m;i++)
	{
		int a,b;
		double c;
		cin>>a>>b>>c;
		edge(a,b,1-c/100);
		edge(b,a,1-c/100);
	}
	int a,b;
	cin>>a>>b;
	dij(a);
	printf("%.8lf",100/dis[b]);
}