#include<fstream>
using namespace std;
int n, total, i, p[10003], c[10003], w[100000003], pmax, minim, j, s;
ifstream f("energii.in");
ofstream g("energii.out");
int main(){
    f>>n>>total;
    minim=99999;
    for(i=1; i<=n; i++){
        f>>p[i]>>c[i];
        s+=c[i];
    }
        for(i=1; i<=s; i++)
            w[i]=99999;
    pmax=0;
    w[0]=0;
    for(i=1; i<=n; i++){
        for(j=pmax; j>=0; j--){
            if(w[j+p[i]]>w[j]+c[i])
                w[j+p[i]]=w[j]+c[i];
            if(j+p[i]>=total && w[j+p[i]]<minim)
                minim=w[j+p[i]];
        }
        pmax+=p[i];
    }
    g<<minim<<"\n";
return 0;
}