#include <bits/stdc++.h>
using namespace std;
struct ab{
	int to,l;
};
int n,m,r[2005],a,b;
double pay[2005];
vector<ab>s[2005];
double ans;
void dfs (double payy,int num){
	pay[num]=payy;
	for (int i=0;i<=s[num].size();i++){
		if (pay[s[num][i].to]>payy/(double)((100-s[num][i].l)/100)){
			dfs(payy/((100-s[num][i].l)/100),s[num][i].to);
			printf("%.8lf\n",payy/((100-s[num][i].l)/100));
		} 
	}
}
int main(){
	cin>>n>>m;
	for (int i=1;i<=n;i++){
		int x,y,z;
		cin>>x>>y>>z;
		r[x]++,r[y]++;
		s[x].push_back((ab){y,z});
		s[y].push_back((ab){x,z});
	}
	for (int i=1;i<=n;i++)
	    pay[i]=9999;
	cin>>a>>b;
	dfs(100,b);
	printf("%.8lf",pay[a]);
	return 0;
}