#include<stdio.h>
 
int max(int n, int W, int w[n], int v[n], int weight, int i){
 
	if (i == n || weight > W) {
        return 0;
    }
 
	if(weight + w[i] <= W){
		int in = v[i] + max(n, W, w, v, weight + w[i], i + 1);
	    int ex = max(n, W, w, v, weight, i + 1);
	    return (in > ex) ? in : ex;
	}
 
	else return max(n, W, w, v, weight, i + 1);
}
 
int main(){
    int n, W;
    scanf("%d %d", &n, &W);
    int w[n], v[n];
    for(int i = 0; i < n; i++){
        scanf("%d %d", &w[i], &v[i]);
    }
    printf("%d", max(n, W, w, v, 0, 0));
}

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NSA2CjMgMQoxIDMKMiAzCjMgNQozIDU=

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3 1
1 3
2 3
3 5
3 5