题解

#include <bits/stdc++.h>
using namespace std;

long long n, m, k, a[1010], sy;

int main(){
    cin >> n >> m >> k;
    for (long long i=1;i<=n;i++){
        cin >> a[i];
    }

    sy = m-k;
    if (sy<=0){ 
        cout << 0; 
        return 0; 
    }

    sort(a+1, a+n+1, greater<long long>());
 
    long long i;
    for (i=1;i<=n;i++){ 
        sy-=a[i]-1;
        if (sy<=0) break;
    }
 
    (sy>0)?cout << "-1":cout << i; 
      
    return 0; 
}