#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("rucsac.in");
ofstream fout("rucsac.out");

struct ghiozdane{
    int pf,gr;
}v[100001];

int n,g,sumgr = 0,prf = 0;
ghiozdane ghiozdan[10000];

int main()
{
    fin >> n >> g;
    for(int i = 1;i<=n;i++){
        fin >> ghiozdan[i].gr >> ghiozdan[i].pf;
    }
    for(int i = 1;i<=n-1;i++){
        for(int j = i+1;j<=n;j++){
            if(ghiozdan[j].pf > ghiozdan[i].pf){
                swap(ghiozdan[j],ghiozdan[i]);
            }
        }
    }
    for(int i = 1;i<=n;i++){
        if(sumgr+ghiozdan[i].gr <= g){
            sumgr+=ghiozdan[i].gr;
            prf+=ghiozdan[i].pf;
        }
    }
    fout << prf;
    return 0;
}