using System; using System.Collections; using System.Collections.Generic; using System.Linq; using System.Text; class TEST{ static void Main(){ Sol mySol =new Sol(); mySol.Solve(); } } class Sol{ public void Solve(){ int N = A.Length ; if(A.Length == 1 && A[0] == 0){ Console.WriteLine(1); return; } int sum = A.Sum() + (N-1); if(sum > M){ Console.WriteLine("NA"); return; } int rest = M - sum; modComb.Init((int)2e6); Console.WriteLine(modComb.nCrMod(rest + N,N)); } int M; int[] A; public Sol(){ M = ri(); A = ria(); } static String rs(){return Console.ReadLine();} static int ri(){return int.Parse(Console.ReadLine());} static long rl(){return long.Parse(Console.ReadLine());} static double rd(){return double.Parse(Console.ReadLine());} static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);} static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));} static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));} static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));} } class modComb{ public static long mod=(long)(1e9+7); public static long nCrMod(long n,long r){ if(n<r)return 0; if(n<0)return 0; if(r<0)return 0; if(n==0||r==n||r==0)return 1; long a=FactorialMod(n); long b=InvMod(FactorialMod(r)); long c=InvMod(FactorialMod(n-r)); long ans=(((a*b)%mod)*c)%mod; return ans; } public static long[] FM; public static void Init(int sz){ FM = new long[sz]; } public static long FactorialMod(long n){ if(FM[(int)n]!=0)return FM[(int)n]; if(n<2)return FM[(int)n]=1; long ret=n*FactorialMod(n-1); ret%=mod; return FM[(int)n]=ret; } public static long PowMod(long n,long k){ if(k==0)return 1; if(n==0)return 0; long ret=1; long x=n; while(k>0){ if((k&1)==1){ret*=x;ret%=mod;} x*=x;x%=mod; k>>=1; } return ret; } public static long InvMod(long n){ //(mod-2)乗を返す // modが素数の時だけ!!!! return PowMod(n,mod-2); } }