#include <bits/stdc++.h>

using namespace std;

#define GMAX 1010

int x,y,a[5010];
int g,c,i,j,b,mx;

int main()
{
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    scanf("%d%d",&g,&c);
    mx=0;
    a[0]=1;
    for (i=1;i<=g;i++){
        scanf("%d%d",&x,&y);
        for (j=0;j<=mx;j++){
            if (a[j]>0){
                b=j+x;
                if (b>c) b=c;
                if (a[b]>a[j]+y||a[b]==0) a[b]=a[j]+y;
                if (b>mx&&b<c) mx=b;
            }
        }
    }
    printf("%d",a[c]-1);
    return 0;
}