//v / wが大きいほうから詰めていく嘘貪欲（もちろんＷＡ）
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std;

struct Baggage {
	double key;
	long long v, w;
	Baggage() {}
	Baggage(long long v, long long w) {
		this->v = v;
		this->w = w;
		key = (double)v / w;
	}
	bool operator>(const Baggage &r) const {
		return key > r.key;
	}
};

int n;
long long w;
Baggage bag[5000];

int main() {
	int i;
	
	cin >> n >> w;
	for (i = 0; i < n; i++) {
		long long v, w;
		cin >> v >> w;
		bag[i] = Baggage(v, w);
	}
	sort(bag, bag + n, greater<Baggage>());
	
	long long remW = w;
	long long sumV = 0;
	for (i = 0; i < n; i++) {
		if (remW >= bag[i].w) {
			remW -= bag[i].w;
			sumV += bag[i].v;
		}
	}
	cout << sumV << endl;
	return 0;
}