#include <iostream>
#include <fstream>
#define N 1011
#define G 5011
#define oo 2000000000

using namespace std;

ifstream f("energii.in");
ofstream g("energii.out");

int a[N][G],w[N],v[N],i,j,x,y,n,m,k,t,p,gmax,r;

int main()
{
    f>>n>>gmax;
    for(i=1;i<=n;i++)
    {
        f>>v[i]>>w[i];
    }
    int l=0;
    for(int i=1;i<=n;++i)
        for(j=1;j<=gmax;++j)
        a[i][j]=oo;
    for(i=1;i<=v[1];++i)
        a[1][i]=w[i];
    for(i=2;i<=n;++i)
    {
        for(j=1;j<=gmax;j++)
        {
            a[i][j]=a[i-1][j];
            if(j-v[i]>0)
            {
                a[i][j]=min(a[i][j],a[i-1][j-v[i]]+w[i]);
            }
            else
                a[i][j]=min(a[i][j],w[i]);
        }
    }
    g<<a[n][gmax];
}