#include<bits/stdc++.h>

using namespace std;

int main()
{
	int N;

    long long W;
    
    cin >> N >> W;
    
    vector<long long> v(N), w(N);

    for (int i = 0; i < N; ++i) {
    	cin >> v[i] >> w[i];
    }

    long long ans = 0;

    long long bestv = 0, bestw = 1;
    long long maxw = 0;

    for (int i = 0; i < N; ++i) {
        if (W < w[i]) continue;
        if (bestv * w[i] < v[i] * bestw) {
            bestv = v[i];
            bestw = w[i];
        }
        if (maxw < w[i]) {
            maxw = w[i];
        }
    }

    for (int i = 0; i < (1 << N); ++i) {
        long long curw = W;
        long long curans = 0;
        for (int j = 0; j < N; ++j) {
            if ((1 << j) & i) {
                curans += v[j];
                curw -= w[j];
            }
        }
        if (curw < 0) continue;
        curans += (curw / bestw) * bestv;
        if (curans > ans) ans = curans;
    }
    
    cout << ans << endl;
}