#include <cstdio>
#include <algorithm>
#define V first
#define W second
using namespace std;
typedef pair<long long,long long> pll;

int n;
long long m,ans;
pll item[5010];

bool flag[5010];

bool cmp(pll a,pll b)
{
    return 1.0*a.V/a.W > 1.0*b.V/b.W;
}

void dfs(long long v,long long w)
{
    int i;
    long long nv = v,nw = w;

    for(i=1;i<=n;i++) if(!flag[i])
    {
        if(nw + item[i].W <= m)
        {
            nv += item[i].V, nw += item[i].W;
            if(nw == m) { ans = max(ans,nv); return; }
        }
        else
        {
            if((long long)(nv + 1.0*(m-nw)/item[i].W*item[i].V) <= ans) return;
            break;
        }
    }
    ans = max(ans,nv);
    if(i > n) return;

    flag[i] = true;
    dfs(v,w);
    if(w + item[i].W <= m) dfs(v+item[i].V,w+item[i].W);
    flag[i] = false;
}

int main()
{
    int i;

    scanf("%d%lld",&n,&m);
    for(i=1;i<=n;i++) scanf("%lld%lld",&item[i].V,&item[i].W);
    sort(item+1,item+n+1,cmp);

    dfs(0,0);
    printf("%lld",ans);
    return 0;
}