#include "bits/stdc++.h" using namespace std; typedef long long ll; typedef pair pii; typedef pair pll; const int INF = 1e9; const ll LINF = 1e18; inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; } inline ll lcm(ll a, ll b) { return a / gcd(a, b)*b; } template ostream& operator << (ostream& out,const pair& o){ out << "(" << o.first << "," << o.second << ")"; return out; } template ostream& operator << (ostream& out,const vector V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; } template ostream& operator << (ostream& out,const vector > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; } template ostream& operator << (ostream& out,const map mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; } /* 問題文============================================================ ================================================================= 解説============================================================= ================================================================ */ const ll MOD = 1e9+7; string solve(){ string res; ll M; cin >> M; vector H; ll h; while(cin >> h){ H.push_back(h); } if(H[0] == 0) return to_string(1); if(accumulate(H.begin(),H.end(),0LL)+H.size()-1 > M) return "NA"; vector> dp(M+3,vector(H.size()+1)); dp[1][0] = 1; for(int i = 1; i <= M+1;i++){ for(int j = 0; j < H.size();j++){ if(dp[i][j] == 0) break; (dp[i+1][j] += dp[i][j])%=MOD; if(i+H[j]+1 <= M+2) (dp[i+H[j]+1][j+1] += dp[i][j])%=MOD; } (dp[i+1][H.size()] += dp[i][H.size()])%=MOD; } //cout << dp << endl; return res = to_string(dp[M+2][H.size()]); } int main(void) { cin.tie(0); ios_base::sync_with_stdio(false); cout << solve() << endl; return 0; }