import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;

class Main {
	long ans = 0;
	int N;
	long W;
	long[][] a;

	void dfs(int curPos, long curWeight, long curValue) {
		ans = Math.max(ans, curValue);
		if (curPos >= N)
			return;
		{
			long resWeight = W - curWeight;
			double relaxAns = curValue;
			for (int i = N - 1; i >= curPos && resWeight != 0; --i) {
				if (resWeight >= a[i][1]) {
					relaxAns += a[i][0];
					resWeight -= a[i][1];
					ans = Math.max(ans, (long) relaxAns);
				} else {
					relaxAns += 1.d * a[i][0] * (1.d * resWeight / a[i][1]);
					resWeight = 0;
				}
			}
			if (relaxAns <= ans) {
				return;
			}
		}
		dfs(curPos + 1, curWeight, curValue);
		if (curWeight + a[curPos][1] <= W) {
			dfs(curPos + 1, curWeight + a[curPos][1], curValue + a[curPos][0]);
		}
	}

	void run() {
		Scanner sc = new Scanner(System.in);
		N = sc.nextInt();
		W = sc.nextLong();
		a = new long[N][2];
		for (int i = 0; i < N; ++i) {
			a[i][0] = sc.nextLong();//value
			a[i][1] = sc.nextLong();//weight
		}
		Arrays.sort(a, new Comparator<long[]>() {
			@Override
			public int compare(long[] arg0, long[] arg1) {
				return Double.compare((double) arg0[0] / arg0[1], (double) arg1[0] / arg1[1]);
			}
		});
		dfs(0, 0, 0);
		System.out.println(ans);
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	public static void main(String[] args) {
		new Main().run();
	}

}