#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<queue>
using namespace std;
typedef pair<double,int> P;
double d[200010];
int cnt=1,t,n,m,s,head[200010];
priority_queue<P,vector<P>,greater<P> > q;
struct Edge{
	double w;
	int to;
	int next;
}edge[200010];
void add(int u,int v,double w)
{
	edge[cnt].w=1.0-w/100;
	edge[cnt].to=v;
	edge[cnt].next=head[u];
	head[u]=cnt++;
}
void dij(int s)
{
	d[s]=1.0;
	q.push(P(1.0,s));
	while(!q.empty())
	{
		P p=q.top();//将最小值赋值
		q.pop();//弹出 
		int u=p.second;
		if(d[u]>p.first) continue;
		else
		{
			for(int i=head[u];i!=-1;i=edge[i].next)
			{
				int v=edge[i].to;
				if(d[v]<d[u]*edge[i].w)
				{
					d[v]=d[u]*edge[i].w;
					q.push(P(d[v],v));//入队 
				}
			}
		} 
	} 
}
int main()
{
	cin>>n>>m;
	memset(head,-1,sizeof(head));
	memset(d,0x3f,sizeof(d));
	for(int i=1;i<=m;i++)
	{
		double w;
		int u,v;
		cin>>u>>v>>w;
		add(u,v,w);
		add(v,u,w);
	}
	cin>>s>>t;
	dij(t);
	printf("%.8lf",100/d[s]);
	return 0;
}