#include <bits/stdc++.h>
using namespace std;
int n, t, m[105], v[105], f;
double b[105], ans = 0.0;

int main() {
	scanf("%d%d", &n, &t);
	for (int i = 1; i <= n; i++) {
		scanf("%d%d", &m[i], &v[i]);
	}
	for (int i = 1; i <= n; i++) {
		b[i] = double(v[i] / m[i]);
	}
	for (int i = 1; i <= n; i++)
		for (int j = i + 1; j <= n; j++) {
			if (b[j] > b[i]) {
				f = b[i];
				b[i] = b[j];
				b[j] = f;
				f = m[i];
				m[i] = m[j];
				m[j] = f;
				f = v[i];
				v[i] = v[j];
				v[j] = f;
			}
		}
	for (int i = 1;; i++) {
		if (t == 0)
			break;
		if (m[i] <= t) {
			t -= m[i];
			ans += v[i];
		}
		if (m[i] > t) {
			ans += double(b[i] * t);
			break;
		}
	}
	printf("%.2lf", ans);
	return 0;
}