#include<cstdio>
#include<queue>
#include<algorithm>
#define N 500005
#define clear(arr,b) for(int i=1;i<N;i++)arr[i]=b
using namespace std;
int head[N],to[N],nxt[N];double val[N];int n,m,s,t,tot,cnt,mi=0x7fffff,stt;double dis[N];
bool vis[N];
void add(int u,int v,double w){
	to[++tot]=v;
	nxt[tot]=head[u];
	head[u]=tot;
	val[tot]=w;
}
void dijkstra(int s){
	priority_queue<pair<int ,int > >q;
	clear(dis,1<<31-1);
	clear(vis,0);
	dis[s]=1.0;
	q.push(make_pair(1.0,s));
	while(!q.empty()){
		int x=q.top().second;q.pop();
		if(vis[x])continue;
		vis[x]=1;
		for(int i=head[x];i;i=nxt[i]){
			int y=to[i];double w=val[i];
			if(dis[y]>dis[x]*w){
				dis[y]=dis[x]*w;
				if(!vis[y])q.push(make_pair(dis[y],y));
			}
		}
	}
}
int main(void){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		int a,b;
		double c;
		scanf("%d%d%lf",&a,&b,&c);
		c=1.0-c/100.0;
		add(a,b,c);
		//add(b,a,c);
	}
	int s,b;
	scanf("%d%d",&s,&b);
	dijkstra(s);
	printf("%.8lf ",100/dis[b]);
	return 0;
}