using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static System.Math;
using static ABC156.Cin;
using static ABC156.Util;
using Pair = ABC156.VTuple<long, long>;
using Graph = System.Collections.Generic.List<System.Collections.Generic.List<long>>;

namespace ABC156
{
    public class Program
    {
        static void Main(string[] args)
        {
            Abc157_C();
        }

        public static void Abc157_F()
        {

        }

        public static void Abc157_E()
        {

        }

        public static void Abc157_D()
        {
           
        }

        public static void Abc157_C()
        {
long n=rl;
long m=rl;
long[] s,c;
ReadCols(out s, out c, m);

long min = (long)Math.Pow(10,n-1);
if(n==1)min=0;
long max = (long)Math.Pow(10,n) -1;
for(int i=(int)min; i<=max;i++){
var keta = new long[3];
FillArray(keta,-1);
keta[0]=0;
int len=0;
for(int j =0; j<3;j++){
var t = i/ (long)Math.Pow(10,j);
if(t==0) continue;
len=j;
keta[j]=t%10;
}


bool b=true;
for(int j =0; j<m;j++){
if(len-(s[j]-1) < 0){
Console.WriteLine(-1);
return;
}
b =b&&keta[len-(s[j]-1)]==c[j];
}
if(b){
Console.WriteLine(i);
return;
}
}
            
Console.WriteLine(-1);
        }

        public static void Abc157_B()
        {
long[][] a = ReadLongTable(3);
long n = rl;
HashSet<long> hs = new HashSet<long>();
for(int i = 0; i < n; i++)
{
hs.Add(rl);
}

for(int i = 0; i < 3; i++)
{
bool b=true;
for(int j = 0; j < 3; j++)
{
b=b&&hs.Contains(a[i][j]);
}
if(b){
Console.WriteLine("Yes");
return;
}
}

for(int i = 0; i < 3; i++)
{
bool b=true;
for(int j = 0; j < 3; j++)
{
b=b&&hs.Contains(a[j][i]);
}
if(b){
Console.WriteLine("Yes");
return;
}
}

bool c=true;
for(int j = 0; j < 3; j++)
{
c=c&&hs.Contains(a[j][j]);
}
if(c){
Console.WriteLine("Yes");
return;
}

c=true;
for(int j = 0; j < 3; j++)
{
c=c&&hs.Contains(a[2-j][j]);
}
if(c){
Console.WriteLine("Yes");
return;
}

Console.WriteLine("No");



        }

        public static void Abc157_A()
        {
           long N = rl;
           Console.WriteLine((N+1)/2);

        }
    }

    public struct Mint
    {
        public static long MOD = (long)1e9 + 7;

        /// <summary>
        /// 0以上MOD未満の整数
        /// </summary>
        public long Value;

        public Mint(long val)
        {
            Value = val % MOD;
            if (Value < 0) Value += MOD;
        }

        private static Mint Ctor(long val)
        {
            return new Mint() { Value = val };
        }

        public static Mint operator +(Mint a, Mint b)
        {
            long res = a.Value + b.Value;
            if (res > MOD) res -= MOD;
            return Ctor(res);
        }
        public static Mint operator -(Mint a, Mint b)
        {
            long res = a.Value - b.Value;
            if (res < 0) res += MOD;
            return Ctor(res);
        }

        public static Mint operator *(Mint a, Mint b)
        {
            long res = a.Value * b.Value;
            if (res > MOD) res %= MOD;
            return Ctor(res);
        }

        public static Mint operator /(Mint a, Mint b)
        {
            return a * Inv(b);
        }

        public static Mint Pow(Mint a, long n)
        {
            if (n == 0) return new Mint(1);
            Mint b = Pow(a, n >> 1);
            b *= b;
            if ((n & 1) == 1) b *= a;
            return b;
        }

        public static Mint Inv(Mint n)
        {
            long a = n.Value;
            long b = MOD;

            long x = 1;
            long u = 0;
            while (b != 0)
            {
                long k = a / b;
                long _x = u;
                u = x - k * u;
                x = _x;

                long _a = a;
                a = b;
                b = _a - (k * b);
            }

            return new Mint(x);
        }

        public override string ToString()
        {
            return Value.ToString();
        }

        public static implicit operator Mint(long a) { return new Mint(a); }
        public static explicit operator long(Mint a) { return a.Value; }
    }

    public class HashMap<K,V>:Dictionary<K,V>{V i;static Func<V>j=System.Linq.Expressions.Expression.Lambda<Func<V>>(System.Linq.Expressions.Expression.New(typeof(V))).Compile();public HashMap(){}public HashMap(V a){i=a;}new public V this[K a]{get{V b;if(TryGetValue(a,out b))return b;else return base[a]=i!=null?i:j();}set{base[a]=value;}}}public static class Util{public static readonly long INF=(long)1e17;public readonly static long MOD=(long)1e9+7;public static void DontAutoFlush(){var a=new System.IO.StreamWriter(Console.OpenStandardOutput()){AutoFlush=false};Console.SetOut(a);}public static void Flush(){Console.Out.Flush();}public static T[]Sort<T>(T[]a){Array.Sort<T>(a);return a;}public static T[]SortDecend<T>(T[]a){Array.Sort<T>(a);Array.Reverse(a);return a;}public static void Swap<T>(ref T a,ref T b){T c=a;a=b;b=c;}public static int GCD(int a,int b){return(b==0)?a:GCD(b,a%b);}public static void ChMax(ref long a,long b){if(a<b)a=b;}public static void ChMin(ref long a,long b){if(a>b)a=b;}public static long ModAdd(long a,long b){long c=a+b;if(c>=MOD)return c%MOD;return c;}public static long ModMul(long a,long b){long c=a*b;if(c>=MOD)return c%MOD;return c;}public static void ChModAdd(ref long a,long b){a+=b;if(a>=MOD)a%=MOD;}public static void ChModMul(ref long a,long b){a*=b;if(a>=MOD)a%=MOD;}public static void FillArray<T>(T[]a,T b){int c=a.Length;for(int d=0;d<c;d++)a[d]=b;}public static void FillArray<T>(T[,]a,T b){int c=a.GetLength(0);int d=a.GetLength(1);for(int e=0;e<c;e++)for(int f=0;f<d;f++){a[e,f]=b;}}public static void FillArray<T>(T[,,]a,T b){int c=a.GetLength(0);int d=a.GetLength(1);int e=a.GetLength(2);for(int f=0;f<c;f++)for(int g=0;g<d;g++){for(int h=0;h<e;h++){a[f,g,h]=b;}}}public static long[]Accumulate(long[]a){long[]b=new long[a.Length+1];for(int c=0;c<a.Length;c++)b[c+1]=b[c]+a[c];return b;}public static double[]Accumulate(double[]a){double[]b=new double[a.Length+1];for(int c=0;c<a.Length;c++)b[c+1]=b[c]+a[c];return b;}}public static class Cin{public static long rl{get{return ReadLong();}}public static long[]rla{get{return ReadLongArray();}}public static double rd{get{return ReadDouble();}}public static double[]rda{get{return ReadDoubleArray();}}public static string rs{get{return ReadString();}}public static int ReadInt(){return int.Parse(k());}public static long ReadLong(){return long.Parse(k());}public static double ReadDouble(){return double.Parse(k());}public static string ReadString(){return k();}public static int[]ReadIntArray(){i=null;return Array.ConvertAll(Console.ReadLine().Split(' '),int.Parse);}public static long[]ReadLongArray(){i=null;return Array.ConvertAll(Console.ReadLine().Split(' '),long.Parse);}public static double[]ReadDoubleArray(){i=null;return Array.ConvertAll(Console.ReadLine().Split(' '),double.Parse);}public static void ReadCols(out long[]a,out long[]b,long c){a=new long[c];b=new long[c];for(int d=0;d<c;d++){a[d]=ReadLong();b[d]=ReadLong();}}public static void ReadCols(out long[]a,out long[]b,out long[]c,long d){a=new long[d];b=new long[d];c=new long[d];for(int e=0;e<d;e++){a[e]=ReadLong();b[e]=ReadLong();c[e]=ReadLong();}}public static int[][]ReadIntTable(int a){i=null;int[][]b=new int[a][];for(int c=0;c<a;c++)b[c]=ReadIntArray();return b;}public static long[][]ReadLongTable(long a){i=null;long[][]b=new long[a][];for(long c=0;c<a;c++)b[c]=ReadLongArray();return b;}static string[]i{get;set;}static int j{get;set;}static string k(){if(i==null||i.Length<=j){i=Console.ReadLine().Split(' ');j=0;}return i[j++];}}public struct VTuple<T1,T2>:IComparable<VTuple<T1,T2>>,IEquatable<VTuple<T1,T2>>{public T1 First;public T2 Second;public VTuple(T1 a,T2 b){First=a;Second=b;}public int CompareTo(VTuple<T1,T2>a){int b=Comparer<T1>.Default.Compare(First,a.First);if(b!=0)return b;return Comparer<T2>.Default.Compare(Second,a.Second);}public override bool Equals(object a){return a is VTuple<T1,T2>&&Equals((VTuple<T1,T2>)a);}public bool Equals(VTuple<T1,T2>a){return EqualityComparer<T1>.Default.Equals(First,a.First)&&EqualityComparer<T2>.Default.Equals(Second,a.Second);}public override int GetHashCode(){int a=First!=null?First.GetHashCode():0;int b=Second!=null?Second.GetHashCode():0;uint c=((uint)a<<5)|((uint)a>>27);return((int)c+a)^b;}}
}


Measured memory_bytes: 13140