#include <iostream>
#include <cstdio>
using namespace std;

unsigned short n,w,g=10000005;
unsigned short p[1005],c[1005];
unsigned short sol[10000005];

int main()
{
    int i,j,mini=1000000,stot=0;
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    scanf("%d%d",&n,&w);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&p[i],&c[i]);
        stot+=p[i];
    }
    if(stot<w)
    {
        printf("-1"); return 0;
    }
    for(i=1;i<=n;i++)
        for(j=g-c[i];j>=0;j--)
            {
                if(sol[j]+p[i]>sol[j+c[i]] ) sol[j+c[i]]=sol[j]+p[i];
                if(sol[j+c[i]]>=w && mini>j+c[i]) mini=j+c[i];
            }
    printf("%d\n",mini);
    fclose(stdin);
    fclose(stdout);
    return 0;
}