#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;

long long solve(int n,long long M,const vector<int> &x){
	vector<long long> v(n);v[0]=1;
	for(int i=1;i<n;i++)for(auto &e:x){
		if(e<=i)v[i]=(v[i]+v[i-e])%M;
	}
	return v[n-1];
}

int main(){
	int n,m;
	scanf("%d%d",&n,&m);
	vector<int>x(m);
	for(int i=0;i<m;i++)scanf("%d",&x[i]);
	printf("%lld\n",solve(n,100000000000000007LL,x));
}