#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
struct coin {
	int m, v;
} a[110];
bool cmp(coin x, coin y) {
	return x.v * y.m > y.v * x.m;
}
int main() {
	int n, t, c, i;
	float ans = 0;
	cin >> n >> t;
	c = t;
	for (int i = 0; i < n; i++) {
		cin >> a[i].m >> a[i].v;
	}
	sort(a, a + n, cmp);
	for (int i = 0; i < n; i++) {
		if (a[i].m > c) {
			break;
		}
		c -= a[i].m;
		ans += a[i].v;
	}
	if (i < n) {
		ans += 1.0 * c / a[i].m * a[i].v;
	}
	printf("%.2lf", ans);
	return 0;
}