#include <cstdio>
#include <iostream>

#define NMAX 5000

using namespace std;

typedef struct {
    int weight, value;
} THING;

int n, W;
THING things[NMAX];

int bruteForce(int current, int weight) {
    if (W < weight) return -500000000;
    if (n == current) return 0;
    return max(things[current].value + bruteForce(current + 1, weight + things[current].weight), bruteForce(current + 1, weight));
}

int main() {
    freopen("rucsac.in", "r", stdin);
    freopen("rucsac.out", "w", stdout);

    cin >> n >> W;
    for (int it = 0; it < n; ++it) {
        cin >> things[it].weight >> things[it].value;
    }
    cout << bruteForce(0, 0);

    return 0;
}