#include <bits/stdc++.h>
#define INF (int)2e9
#define Nmax 10001
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int a[2][Nmax];
int e[Nmax];
int c[Nmax];
int main()
{
    int G,n,i,j;
    f>>n>>G;
    for(i=1;i<=n;i++)
        f>>e[i]>>c[i];
    bool cur=0,curr=1;
    for(i=1;i<=G+12000;i++)
        a[0][i]=INF;
    for(i=1;i<=n;i++)
    {
        cur^=1;
        curr^=1;
        for(j=1;j<=G+12000;j++)
        {
            a[cur][j]=a[curr][j];
            if(j-e[i]<0) continue;
            a[cur][j]=min(a[cur][j],a[curr][j-e[i]]+c[i]);
        }
    }
    int minn=INF;
    for(i=G;i<=G+12000;i++)
        if(a[cur][i]<minn) minn=a[cur][i];
    if(minn==INF) g<<-1;
    else g<<minn;

    return 0;
}