#include<bits/stdc++.h>
using namespace std;
int n, t, d, i;
struct c {
	int m, v;
}a[108];
bool cmp(c x, c y) {
	return x.v * y.m > y.v * x.m;
}
int main() {
	float ans = 0;
	cin >> n >> t;
	d = 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 > d) {
			break;
		}
		d -= a[i].m;
		ans += a[i].v;
	}
	if (i < n) {
		ans += 1.0 * d / a[i].m * a[i].v;
	}
	printf("%.2f", ans);

	return 0;
}