#include <bits/stdc++.h>
using namespace std;

const int N = 2010;
const int M = 2e5 + 10;

typedef pair<double, int> PDI; // 堆中数值是浮点数，注意区别

int n, m;
double dis[N];
bool st[N];

int h[N], e[M], ne[M], idx;
double w[M]; // 边权为浮点数,与一般的题目有区别
void add(int a, int b, double c) {
    e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
}
int S, T;
void dijkstra() {
    priority_queue<PDI> q; // 大顶堆
    dis[S] = 1;
    q.push({1, S});

    while (q.size()) {
        auto t = q.top();
        q.pop();
        int u = t.second;
        if (st[u]) continue;
        st[u] = true;

        for (int i = h[u]; ~i; i = ne[i]) {
            int v = e[i];
            double a = 1 - w[i];
            if (dis[v] < dis[u] * a) {
                dis[v] = dis[u] * a;
                q.push({dis[v], v});
            }
        }
    }
}

int main() {
    memset(h, -1, sizeof h);
    cin >> n >> m;

    while (m--) {
        int a, b, c;
        cin >> a >> b >> c;
        double w = c * 0.01;
        add(a, b, w), add(b, a, w);
    }

    cin >> S >> T;

    dijkstra();
    printf("%.8lf\n", 100 / dis[T]);
    return 0;
}