#include<cstdio>
#include<algorithm>
using namespace std;
int mat[3][5010];
int main()
{
    int i,j,n,m,c,e,a=1,b=2,E,s;
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    scanf("%d %d",&n,&s);
    for(i=1;i<=n;i++)
    {
        scanf("%d %d",&e,&c);
        for(E=1;E<=s;E++)
        {
            if(e<=E)
            {
                if(mat[b][E-e]==0) mat[b][E]=c;
                else mat[b][E]=min(mat[a][E],mat[b][E-e]+c);
            }
            else mat[b][E]=mat[a][E];
        }
        swap(a,b);
    }
    printf("%d",mat[a][s]);
    return 0;
}