#include <fstream>

#define NMAX 5005

using namespace std;

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

int n,i,j,power;
int  v[NMAX],mini[NMAX],c[NMAX];

int main()
{
    f>>n>>power;
    for(i=1;i<=n;i++)
    {
        f>>v[i]>>c[i];
    }
    for(i=1;i<=power;i++)
        mini[i]=NMAX*3;
    for(i=1;i<=n;i++)
    {
        for(j=power;j>=v[i];j--)
            mini[j]=min(mini[j],mini[j-v[i]]+c[i]);
    }
    g<<mini[power];
}