#include<bits/stdc++.h>
using namespace std;
int n,m;
int w[30001],v[30001];
int flag,ans=0;
int main(){
    freopen("delicious.in","r",stdin);
    freopen("delicious.out","w",stdout);
    cin>>n>>m;
    flag=m;
    for(int i=0;i<n;i++){
        cin>>w[i]>>v[i];
    }
    for(int i=0;i<n;i++){
        int temp1=v[0],temp2=0;
        for(int j=0;j<n;j++){
            if(v[j]>temp1){
                temp1=v[j];
                temp2=j;
            }
        }
        if(flag-w[temp2]>=0){
            flag=flag-w[temp2];
            ans=ans+temp1;
        }
        else{
            cout<<ans<<endl;
            return 0;
        }
    }
    return 0;
}