#include <cstdio>
#include <cstring>
#define MAX 100005
#define INF 500000

using namespace std;

int d[MAX];

int main()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    int n,c,w,g,i,j;
    scanf("%d%d",&n,&g);
    for(i=1;i<=g;i++)
        d[i]=INF;
    d[0]=0;
    for( i=1;i<=n;i++){
        scanf("%d%d",&c,&w);
        for( j=g;j>=0;j--)
            if(d[j]+w<d[j+c])
                d[j+c]=d[j]+w;
    }
    if(d[g]!=INF)
        printf("%d",d[g]);
    else
        printf("-1");
    return 0;
}