#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mx = 1e5+10;
ll n,w;
ll weight[mx];
ll cost[mx];
int solve(ll i,ll we)
{
    ll profit,profit1;
    if(i==n+1)
        return 0;
    if(we+weight[i]<=w)
    {
        profit = cost[i]+solve(i+1,we+weight[i]);
    }
    else profit = 0;

    profit1 = solve(i+1,we);
    return max(profit,profit1);
}
int main()
{
    cin>>n>>w;
    for(int i=0;i<n;i++)
    {
        cin>>weight[i]>>cost[i];
    }
    cout<<(ll)solve(0,0)<<endl;
}