#include <iostream>
#include <fstream>

using namespace std;

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

struct ghiozdane{
    int pf,gr;
}v[10000];

int N,G,sumgr = 0,prf = 0;
ghiozdane ghiozdan[10000];

int main()
{
    fin >> N >> G;
    if(N<=5000 && G <=10000 && G>=1 && N>=1){
        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].gr < ghiozdan[i].gr){
                    swap(ghiozdan[j],ghiozdan[i]);
                }
                if(ghiozdan[i].gr == ghiozdan[j].gr && ghiozdan[i].pf < ghiozdan[j].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;
}