#include <cstdio>
#include <algorithm>
int N,G,g,v,a[50001];
using std::max;
using std::min;

void dp()
{
    scanf("%d %d",&N,&G);
    for(int j = G; j>=1;j--)
        a[j]=(1<<30);
    while(N--)
    {
        scanf("%d %d ",&g,&v);
        for(int j = G ;j >= g; j--)
            a[j]=min(a[j],a[j-g]+v);
    }
    printf("%d",a[G]!=(1<<30)?a[G]:-1);
}

int main()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    dp();
    return 0;
}