/* @author St\'efano Drimon Kurz M\'or */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct _item_t {
	int value;   // v_i
	int weight;  // w_i
	float density; // v_i/w_i
} item_t;

int greater_f(const int x, const int y);
int compare_f(const void *x, const void *y);

int knapsack_f(const int n, const int M, const item_t * const itens) {

	int v = 0, w = 0;
	int r = 0;

	if (n < 1)
		return 0;

	while (M - w >= 0) {
		r = greater_f(r, v + knapsack_f(n - 1, M - w, &(itens[1])));
		v += itens[0].value;
		w += itens[0].weight;
	}

	return r;

}

int main(int argc, const char *argv[]) {

	int n;
	int M;
	item_t *itens;

	int i;

	scanf("%d %d", &n, &M);
	itens = (item_t*) calloc(n, sizeof(item_t));

	for (i = 0; i < n; ++i) {
		scanf("%d %d", &(itens[i].value), &(itens[i].weight));
		itens[i].density = (float) (itens[i].value) / itens[i].weight;
	}

	qsort(itens, (size_t) n, sizeof(item_t), compare_f);

	printf("%d\n", knapsack_f(n, M, itens));

	free(itens);

	return 0;

}

int greater_f(const int x, const int y) {
	return (x > y) ? x : y;
}

int compare_f(const void *x, const void *y) {
	return ((item_t*) x)->density - ((item_t*) y)->density;
}