#include <stdio.h>
#include <algorithm>

using namespace std;

#define ll long long unsigned
#define pb push_back
#define mp make_pair

int EG[1005],CG[1005];
// dp[i] = pretul minim pt a produce i energie

int main(){
    int G,W,j;
    freopen("energii.in", "r", stdin);
    freopen("energii.out", "w", stdout);
    scanf("%d",&G);
    scanf("%d",&W);
    for(int i = 1;i <= G;i++){
        scanf("%d %d",&EG[i],&CG[i]);
    }
    int mn = 1e7;
    ll limit = 1;
    for(int i = 1;i <= G;i++){
        limit = 1LL*limit*2;
    }
    for(ll i = 1;i < limit;i++){
        ll aux = i;
        int sum = 0;
        int cost = 0;
        int cnt = 1;
        while(aux){
            if(aux&1){
                sum += EG[cnt];
                cost += CG[cnt];
            }
            aux >>= 1;
            cnt++;
        }
        if(sum >= W){
            mn = min(mn, cost);
        }
    }
    printf("%d",mn);
}