#include<bits/stdc++.h>
using namespace std;
long long w[1010],c[1010],n,g,tot,ans[10010];
int32_t main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cerr.tie(0);
    ifstream cin("energii.in");
    ofstream cout("energii.out");
    cin >> n >> g;
    for(int i = 1; i <= n; i++){
        cin >> w[i] >> c[i];
        tot += c[i];
    }
    memset(ans, 0x3f , sizeof(ans));
    ans[0]=0;
    for(int i = 1; i <= n; i++){
        for(int j = g; j >= w[i]; j--){
            ans[j] = min(ans[j] , ans[j-w[i]] + c[i]);
        }
    }
    if(ans[g]!=0x3f) cout << ans[g];
        else cout<<"-1";
}