#include <fstream>
using namespace std;

ifstream in("energii.in");
ofstream out("energii.out");
int n_generators , req_energy;
struct values{
    int e , p;
};
values v[1001];
int sol[5001];
int main(){
    in >> n_generators >> req_energy;
    for(int i = 1 ; i <= n_generators ; i++){
        in >> v[i].e >> v[i].p;
    }
    for(int i = 1 ; i <= n_generators ; i++){
        for(int j = req_energy ; j >= 1 ; j--){
            if(j > v[i].e){
                if(sol[j - v[i].e] != 0)
                    sol[j] = sol[j - v[i].e] + v[i].p;
            }
            else{
                if(sol[j] != 0)
                    sol[j] = min(sol[j] , v[i].p);
                else{
                    sol[j] = v[i].p;
                }
            }
        }
    }
    out << sol[req_energy];
}