#include <signal.h>

typedef long long ll;
typedef struct{ll v,w,t,u;}S;

int n;
ll c;
ll b;
S ss[6000];

void ha(){
	printf("%lld\n",b);
	exit(0);
}

int sgn(double a){
	return a<0?-1:a>0;
}

int cmp(void*a,void*b){
	S*p=a,*q=b;
	return sgn((double)q->v/q->w-(double)p->v/p->w);
}

void dfs(int i,ll v,ll c){
	if(i==n){
		if(b<v){
			b=v;
		}
	}else{
		if(v+ss[i].t<=b){
			return;
		}
		if(c>=ss[i].w){
			dfs(i+1,v+ss[i].v,c-ss[i].w);
		}
		if(c<ss[i].u){
			dfs(i+1,v,c);
		}
	}
}


main(i){
	scanf("%d%lld",&n,&c);
	for(i=0;i<n;++i){
		scanf("%lld%lld",&ss[i].v,&ss[i].w);
	}
	qsort(ss,n,sizeof(S),cmp);

	ll t=0,u=0;
	for(i=n;i--;){
		ss[i].t=t+=ss[i].v;
		ss[i].u=u+=ss[i].w;
	}
	signal(14,ha);
	ualarm(1900000,0);
	dfs(0,0ll,c);
	raise(14);
}