#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <list>
#include <numeric>
using namespace std;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = 1<<25;
typedef pair<int,int> P;
typedef long long ll;
typedef unsigned long long ull;

ll dp[100010];

int main(){
	ll C, N;
	cin>>C>>N;
	vector<ll> d(N);
	for(int i = 0; i < N; i++) cin>>d[i];
	memset(dp, -1, sizeof(dp));
	dp[C] = 0;
	for(int i = 0; i < N; i++){
		for(int j = C; j >= d[i]; j--){
			if(dp[j]>=0 && (dp[j-d[i]]<0 || dp[j-d[i]]>dp[j]+1)) dp[j-d[i]] = dp[j]+1;
		}
		cerr<<dp[0]<<endl;
	}
	cout<<dp[0]<<endl;
	return 0;
}