题解

#include <iostream>
#include <algorithm>
using namespace std;
int a[1005],n,m,k,sum;
bool flag; 
bool cmp(int x,int y)
{
 	return x>y;
}
int main()
{
 	cin>>n>>m>>k;	
	for(int i=0;i<n;i++)
    {
		cin>>a[i];
	}
	sort(a,a+n,cmp);
	if(k>=m)
    {
		cout<<"0"<<endl;
		return 0;
	}
	else
    {
		sum=k;
		flag=0;
		for(int i=0;i<n;i++)
        {
            sum=sum-1+a[i];
			if(sum>=m)
            {
				cout<<i+1<<endl;
				flag=1;
				break;
			}
		}
		if(flag==0) cout<<"-1"<<endl;
	}
 	return 0;
}