#include <iostream>
#include <fstream>

using namespace std;

struct segment2 {int g,pr;}v[100],aux;
int n,i,j,total,s,g;
int main()
{
    ifstream f("rucsac.in");
    ofstream ge("rucsac.out");
    f>>n>>g;
    for(i=1;i<=n;i++) f>>v[i].g>>v[i].pr;
    for(i=1;i<n;i++)
            if(v[i].pr/v[i].g<v[i+1].pr/v[i+1].g)
                {
                    aux=v[i];
                    v[i]=v[i+1];
                    v[i+1]=aux;
                }
    total=0;
    s=0;
    for(i=1;i<=n;i++)
    {
        s=s+v[i].pr;
        total=total+v[i].g;
        if(total>g) break;
    }
    ge<<s;
    return 0;
}