宣贯

#include<bits/stdc++.h>
using namespace std;
const int N=11;
int n,m,a[N],ans,s=2;//sum
int p;
int main(){
	cin>>m>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+n+1);
	if(a[1]!=1){cout<<-1;return 0;}
	while(s<m){
		for(int i=n;i>=1;i--) if(a[i]<s){p=i;break;}
		ans++,s+=a[p];
	}
	cout<<ans<<"\n";
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=11;
int n,m,a[N],ans,s;//sum
int p;
int main(){
	cin>>m>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+n+1);
	if(a[1]!=1){cout<<-1;return 0;}
	while(s<m){
		for(int i=n;i>=1;i--) if(a[i]<s+2){p=i;break;}
		ans++,s+=a[p];
	}
	cout<<ans<<"\n";
	return 0;
}