#include <bits/stdc++.h>
using namespace std;
 
const int N=22;
int n, c[N], v[N];
long long ans, S;
 
void btrack(int idx, long long cost, long long val)
{
    if(idx>n){
        if(cost<=S) ans=max(ans, val);
        return;
    }
    btrack(idx+1, cost+c[idx], val+v[idx]); //chọn vị trí idx
    btrack(idx+1, cost, val); //không chọn vị trí idx
}
 
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
 
    cin >> n >> S;
    for(int i=1;i<=n;++i)
        cin >> c[i] >> v[i];
    btrack(1, 0, 0);
    cout << ans;
    return 0;
}
 

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