#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
long long n, l, v1, v2, k;
cin >> n >> l >> v1 >> v2 >> k;
double low = 0, high = double(l) / v1;
int trips = (n + k - 1) / k;
for (int it = 0; it < 100; ++it) {
double mid = 0.5*(low + high);
// Tính D theo công thức
double D = (v1 * v2 * (mid - double(l)/v1)) / (v1 - v2);
if (D <= 0) {
// Đi bộ cũng kịp
high = mid;
continue;
}
if (D > l) {
// Cần đi buýt dài hơn quãng đường => không khả thi
low = mid;
continue;
}
// Thời gian buýt chạy tất cả các chuyến
double tbus = (2.0 * trips - 1.0) * (D / v2);
if (tbus <= mid) high = mid;
else low = mid;
}
cout << fixed << setprecision(9) << high << "\n";
return 0;
}
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