#include<bits/stdc++.h>
using namespace std;
const int N=1e4+5;
double dis[N];
bool vis[N];
vector<pair<int,int> > e[N]; 
struct Node
{
	int id;
	double val;
	friend bool operator <(Node x,Node y)
	{
		return x.val>y.val;
	}
};
priority_queue<Node> q;
int main()
{
	int n,m,a,u,v,b;
	double w;
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++) dis[i]=-2000000000;
	for(int i=1;i<=m;i++)
	{
		scanf("%d%d%lf",&u,&v,&w);
		e[u].push_back(make_pair(v,1-w/100.0));
		e[v].push_back(make_pair(u,1-w/100.0));
	}
	scanf("%d%d",&a,&b);
	dis[a]=100.0;
	vis[a]=1;
	q.push((Node){a,dis[a]});
	while(!q.empty())
	{
		u=q.top().id;
		q.pop();
		if(vis[u]) continue;
		vis[u]=true;
		for(int i=0;i<e[u].size();i++)
		{
			v=e[u][i].first;
			w=e[u][i].second;
			if(vis[v]) continue;
			if(dis[v]>dis[u]*w)
			{
				dis[v]=dis[u]*w;
				q.push((Node){v,dis[v]}); 
			}
		}
	}
	printf("%.8lf",dis[b]);
	return 0;
}

对了会关的，很急，谢谢！