#include <stdio.h>
#define MAXN 1000


short int w[MAXN],v[MAXN],a[MAXN][MAXN];

int nro,bestsol = 0;

int best(int v1,int v2)
{
	if (v1>v2)
	{
		return v1;
	}
	return v2;
}

int ks(int start,int c)
{
	if (start>nro)
	{
		return 0;
	}
	if (w[start]>c)
	{
		return ks(start+1,c);
	}
	return best(ks(start+1,c),v[start]+ks(start+1,c-w[start]));
}

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

	scanf("%d%d",&nro,&c);
	for (i=1;i<=nro;i++)
	{
		scanf("%d",&w[i]);
		scanf("%d",&v[i]);
	}

	printf("%d",ks(1,c));

	return 0;
}