#include <bits/stdc++.h>
using namespace std;
const int N=30000+5;
struct sdf{
    bool ok;
    int pt;
}p[1005][1005];
int f[N]={0};
int w[N],v[N],s[N]={0},ne=0;
int main(){
    freopen ("delicious.in","r",stdin);
    freopen ("delicious.out","w",stdout);
    int n,m;
    cin>>n>>m;
    for (int i=1;i<=n;i++){
        int a,b;
        scanf("%d%d",&a,&b);
        if (p[a][b].ok==0){
            w[++ne]=a;
            v[ne]=b;
            s[ne]++;
            p[a][b].pt=ne;
        }
        else{
            s[p[a][b].pt]++;
        }
    }
    for (int i=1;i<=ne;i++){
        int mx=-1;
        for (int j=0;(1<<j)<s[i];j++){
            mx=j;
            for (int k=m;k>=w[i]*(1<<j);j--){
                f[k]=max(f[k],f[k-w[i]*(1<<j)]+v[i]*(1<<j));
            }
        }
        int x;
        if (mx==-1)x=s[i];
        else x=s[i]-(1<<mx);
        for (int j=m;j>=w[i]*x;j--){
            f[j]=max(f[j],f[j-w[i]*x]+v[i]*x);
        }
    }
    cout<<f[m]<<endl;
    return 0;
}