using System; using System.Collections.Generic; using System.Collections; using System.Collections.Specialized; using System.Linq; using System.Text; using System.IO; using System.Reflection; using static System.Math; using System.Numerics; using System.Threading; using System.Runtime.CompilerServices; //using nint=System.Int32; static class Program{ const int mod=(int)1e9+7; //const double eps=1e-11; static void Main(){ Sc sc=new Sc(); var n=sc.I; var a=sc.Ia; if(a.Min()==0){ Console.WriteLine(-1); return; } var r=new long[4]; r[0]=1; for(int i = 1;i3){ Console.WriteLine(mod); return; } p*=r[a[i]]; if(p>mod){ Console.WriteLine(mod); return; } } Console.WriteLine(mod%p); } } public class Sc{ public int I{get{return int.Parse(Console.ReadLine());}} public long L{get{return long.Parse(Console.ReadLine());}} public double D{get{return double.Parse(Console.ReadLine());}} public string S{get{return Console.ReadLine();}} public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}} public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}} public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}} public string[] Sa{get{return Console.ReadLine().Split();}} public object[] Oa{get{return Console.ReadLine().Split();}} public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}} public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);} public int[] Ia3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),int.Parse);} public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}} public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);} public long[] La3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),long.Parse);} public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}} public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);} public T[] Arr(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i(int n,Func f){var a=new T[n];for(int i=0;i