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

using ll=long long;
const ll MOD=100000000000000007;


int main(){
    int n,m;
    cin>>n>>m;
    vector<int> x(m);
    for(int i=0;i<m;i++) cin>>x[i];
    sort(x.begin(),x.end());
    vector<int> belong(m);
    for(int i=0;i<m;i++) belong[i]=i;
    vector<deque<ll>> dp(m);
    for(int i=0;i<n;i++){
        for(int j=0;j<m-1;j++){
            if(i+x[j]==x[j+1]){
                while(!dp[belong[j+1]].empty()){
                    dp[belong[j]].push_back(dp[belong[j+1]].front());
                    dp[belong[j+1]].pop_front();
                }                                
                belong[j+1]=belong[j];
            }
        }
        if(i<x[0]){
            ll step=(i==0);
            for(int j=0;j<m;j++){
                if(i+x[j]<n){
                    int to=i+x[j]-x[belong[j]];
                    if(dp[belong[j]].size()>to){
                        dp[belong[j]][to]+=step;
                        if(dp[belong[j]][to]>=MOD){
                            dp[belong[j]][to]-=MOD;
                        }
                    }
                    else dp[belong[j]].push_back(step);
                }
            }
        }
        else{
            ll step=dp[0].front();
            dp[0].pop_front();
            for(int j=0;j<m;j++){
                if(i+x[j]<n){                                        
                    int to=(belong[j]==0 ? x[j]-1 : i+x[j]-x[belong[j]]);
                    if(dp[belong[j]].size()>to){
                        dp[belong[j]][to]+=step;
                        if(dp[belong[j]][to]>=MOD){
                            dp[belong[j]][to]-=MOD;
                        }
                    }
                    else dp[belong[j]].push_back(step);
                }
            }
        }
        
    }
    cout<<dp[0].back();
    return 0;
}