#include <iostream>
#include <fstream>
using namespace std;

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

int n,g,val_furt;
int pret[10],vol[10];

int main(){
    fin>>n>>g;
    for(int i=1;i<=n;i++){
        fin>>vol[i]>>pret[i];
    }
    for(int j=1;j<n;++j){
        for(int i=j+1;i<=n;i++){
            if(pret[i]/vol[i]<pret[i+1]/vol[i+1]){
                int aux=pret[i];
                pret[i]=pret[i+1];
                pret[i+1]=aux;
                aux=vol[i];
                vol[i]=vol[i+1];
                vol[i+1]=aux;
            }
        }
    }
    for(int i=1;i<=n && g>=0;i++){
        if(g>=vol[i]){
            g-=vol[i];
            val_furt+=pret[i];
        }
    }
    fout << val_furt;
    return 0;
}