#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N;
ll W;
pair<ll,ll> P[5050];
ll ma=0;
ll A[5050],B[5050];
ll SA[5050],SB[5050];

bool cmp(pair<ll,ll> L,pair<ll,ll> R) {
	return L.first*1.0/L.second>R.first*1.0/R.second;
}

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>W;
	FOR(i,N) cin>>P[i].first>>P[i].second;
	while(N<50) P[N]={0,1000000000}, N++;
	sort(P,P+N,cmp);
	FOR(i,N) {
		A[i]=P[i].first;
		B[i]=P[i].second;
		SA[i+1]=SA[i]+A[i];
		SB[i+1]=SB[i]+B[i];
	}
	
	FOR(i,N-20+1) if(SB[i]<=W) {
		if(SB[i+20]<=W) {
			ma=max(ma,SA[i+20]);
		}
		else {
			for(int mask=0;mask<1<<20;mask++) {
				ll tv=SA[i],tw=SB[i];
				FOR(j,20) if(mask&(1<<j)) tv+=A[i+j],tw+=B[i+j];
				if(tw<=W) ma=max(ma,tv);
			}
		}
	}
	
	cout<<ma<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}