2
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 3
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5 5 4 9 1 4
2 1 7 5 1 7
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9 0 6 4 2 8
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0 0 0 0 0 0
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3
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 3
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 29
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 21
 6
 21
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 98
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 32
 19
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 65
 0

/*
 * 
 * @Author  Ajudiya_13(Bhargav Girdharbhai Ajudiya)
 * Dhirubhai Ambani Institute of Information And Communication Technology 
 * 
 */


import java.util.*;
import java.io.*;
import java.lang.*;

public class Code245
{
	
	public static void main(String[] args)
	{
		InputReader in = new InputReader(System.in);
		PrintWriter pw = new PrintWriter(System.out);

		int n = in.nextInt();
		HashSet<Integer> a[] = new HashSet[n];
		for(int i=0;i<n;i++)
			a[i] = new HashSet<Integer>();
		for(int i=0;i<n;i++)
		{
			for(int j=0;j<6;j++)
				a[i].add(in.nextInt());
		}

		if(n==1)
		{
			int ans = -1;
			for(int i=1;i<=9;i++)
			{
				if(a[0].contains(i))
					ans = i;
				else
					break;
			}
			pw.println(ans);
		}
		
		else if(n==2)
		{
			int ans = -1;
			boolean flag = true;
			for(int i=1;i<=9;i++)
			{
				if(a[0].contains(i) || a[1].contains(i))
					ans = i;
				else
				{
					flag = false;
					break;
				}
			}
			
			if(flag)
			{
				for(int i=10;i<=99;i++)
				{
					int temp = i;
					int p = temp%10;
					temp/=10;
					int q = temp%10;
					
					if (a[0].contains(p) && a[1].contains(q))
						ans = i;
					else if(a[0].contains(q) && a[1].contains(p))
						ans = i;
					else
					{
						flag = false;
						break;
					}
				}
			}
			
			pw.println(ans);
		}
		
		else
		{
			int ans = -1;
			boolean flag = true;
			
			for(int i=1;i<=9;i++)
			{
				if(a[0].contains(i) || a[1].contains(i) || a[2].contains(i))
					ans = i;
				else
				{
					flag = false;
					break;
				}
			}
			
			if(flag)
			{
				for(int i=10;i<=99;i++)
				{
					int temp = i;
					int p = temp%10;
					temp/=10;
					int q = temp%10;
					
					if(a[0].contains(p) && a[1].contains(q))
						ans = i;
					else if(a[0].contains(q) && a[1].contains(p))
						ans = i;
					else if(a[0].contains(p) && a[2].contains(q))
						ans = i;
					else if(a[0].contains(q) && a[2].contains(p))
						ans = i;
					else if(a[1].contains(p) && a[2].contains(q))
						ans = i;
					else if(a[1].contains(q) && a[2].contains(p))
						ans = i;
					else
					{
						flag = false;
						break;
					}
				}
			}
			
			if(flag)
			{
				for(int i=100;i<=999;i++)
				{
					int temp = i;
					int p = temp%10;
					temp/=10;
					int q = temp%10;
					temp/=10;
					int r = temp%10;
					
					if(a[0].contains(p) && a[1].contains(q) && a[2].contains(r))
						ans = i;
					else if(a[0].contains(p) && a[1].contains(q) && a[2].contains(r))
						ans = i;
					else if(a[0].contains(q) && a[1].contains(p) && a[2].contains(r))
						ans = i;
					else if(a[0].contains(q) && a[1].contains(r) && a[2].contains(p))
						ans = i;
					else if(a[0].contains(r) && a[1].contains(p) && a[2].contains(q))
						ans = i;
					else if(a[0].contains(r) && a[1].contains(q) && a[2].contains(p))
						ans = i;
					else
					{
						flag = false;
						break;
					}
				}
			}
			pw.println(ans);
		}
		pw.flush();
		pw.close();
	}
	
	static class InputReader 
	{
		 
		private final InputStream stream;
		private final byte[] buf = new byte[8192];
		private int curChar, snumChars;
		private SpaceCharFilter filter;
 
		public InputReader(InputStream stream) 
		{
			this.stream = stream;
		}
 
		public int snext() 
		{
			if (snumChars == -1)
				throw new InputMismatchException();
			if (curChar >= snumChars) 
			{
				curChar = 0;
				try 
				{
					snumChars = stream.read(buf);
				} 
				catch (IOException e) 
				{
					throw new InputMismatchException();
				}
				if (snumChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}
 
		public int nextInt() 
	    {
			int c = snext();
			while (isSpaceChar(c)) 
			{
				c = snext();
			}
			int sgn = 1;
			if (c == '-')
		    {
				sgn = -1;
				c = snext();
			}
			int res = 0;
			do 
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public long nextLong()
	    {
			int c = snext();
			while (isSpaceChar(c)) 
			{
				c = snext();
			}
			int sgn = 1;
			if (c == '-') 
			{
				sgn = -1;
				c = snext();
			}
			long res = 0;
			do 
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = snext();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public int[] nextIntArray(int n) 
		{
			int a[] = new int[n];
			for (int i = 0; i < n; i++) 
			{
				a[i] = nextInt();
			}
			return a;
		}
 
		public String readString()
	    {
			int c = snext();
			while (isSpaceChar(c)) 
			{
				c = snext();
			}
			StringBuilder res = new StringBuilder();
			do 
			{
				res.appendCodePoint(c);
				c = snext();
			} while (!isSpaceChar(c));
			return res.toString();
		}
 
		public String nextLine() 
		{
			int c = snext();
			while (isSpaceChar(c))
				c = snext();
			StringBuilder res = new StringBuilder();
			do 
			{
				res.appendCodePoint(c);
				c = snext();
			} while (!isEndOfLine(c));
			return res.toString();
		}
 
		public boolean isSpaceChar(int c) 
		{
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
 
		private boolean isEndOfLine(int c) 
		{
			return c == '\n' || c == '\r' || c == -1;
		}
 
		public interface SpaceCharFilter
	    {
			public boolean isSpaceChar(int ch);
		}
	}
	
	public static long mod = 1000000007;
	public static int d;
	public static int p;
	public static int q;
	
	public static int[] suffle(int[] a,Random gen)
	{
		int n = a.length;
		for(int i=0;i<n;i++)
		{
			int ind = gen.nextInt(n-i)+i;
			int temp = a[ind];
			a[ind] = a[i];
			a[i] = temp;
		}
		return a;
	}
	
	public static void swap(int a, int b){
		int temp = a;
		a = b;
		b = temp;
	}
	
	public static HashSet<Integer> primeFactorization(int n)
	{
		HashSet<Integer> a =new HashSet<Integer>();
		for(int i=2;i*i<=n;i++)
		{
			while(n%i==0)
			{
				a.add(i);
				n/=i;
			}
		}
		if(n!=1)
			a.add(n);
		return a;
	}
	
	public static void sieve(boolean[] isPrime,int n)
	{
		for(int i=1;i<n;i++)
			isPrime[i] = true;
		
		isPrime[0] = false;
		isPrime[1] = false;
		
		for(int i=2;i*i<n;i++)
		{
			if(isPrime[i] == true)
			{
				for(int j=(2*i);j<n;j+=i)
					isPrime[j] = false;
			}
		}
	}
	
	public static int GCD(int a,int b)
	{
		if(b==0)
			return a;
		else
			return GCD(b,a%b);
	}
	
	public static long GCD(long a,long b)
	{
		if(b==0)
			return a;
		else
			return GCD(b,a%b);
	}
	
	public static void extendedEuclid(int A,int B)
	{
		if(B==0)
		{
			d = A;
			p = 1 ;
			q = 0;
		}
		else
		{
			extendedEuclid(B, A%B);
			int temp = p;
			p = q;
			q = temp - (A/B)*q;
		}
	}
	
	public static long LCM(long a,long b)
	{
		return (a*b)/GCD(a,b);
	}
	
	public static int LCM(int a,int b)
	{
		return (a*b)/GCD(a,b);
	}
	
	public static int binaryExponentiation(int x,int n)
	{
	    int result=1;
	    while(n>0)
	    {
	        if(n % 2 ==1)
	            result=result * x;
	        x=x*x;
	        n=n/2;
	    }
	    return result;
	}
	
	public static long binaryExponentiation(long x,long n)
	{
	    long result=1;
	    while(n>0)
	    {
	        if(n % 2 ==1)
	            result=result * x;
	        x=x*x;
	        n=n/2;
	    }
	    return result;
	}
	
	public static int modularExponentiation(int x,int n,int M)
	{
	    int result=1;
	    while(n>0)
	    {
	        if(n % 2 ==1)
	            result=(result * x)%M;
	        x=(x*x)%M;
	        n=n/2;
	    }
	    return result;
	}
	
	public static long modularExponentiation(long x,long n,long M)
	{
	    long result=1;
	    while(n>0)
	    {
	        if(n % 2 ==1)
	            result=(result * x)%M;
	        x=(x*x)%M;
	        n=n/2;
	    }
	    return result;
	}
	
	public static int modInverse(int A,int M)
	{
	    return modularExponentiation(A,M-2,M);
	}
	
	public static long modInverse(long A,long M)
	{
	    return modularExponentiation(A,M-2,M);
	}
	
	public static boolean isPrime(int n)
	{
	    
	    if (n <= 1)  return false;
	    if (n <= 3)  return true;
	    
	    if (n%2 == 0 || n%3 == 0) 
	    	return false;
	 
	    for (int i=5; i*i<=n; i=i+6)
	    {
	        if (n%i == 0 || n%(i+2) == 0)
	           return false;
	    }
	    
	    return true;
	}
	
	static class pair implements Comparable<pair>
	{
		Integer x, y;
		pair(int x,int y)
		{
			this.x=x;
			this.y=y;
		}
		
		public int compareTo(pair o) {
			int result = x.compareTo(o.x);
			if(result==0)
				result = y.compareTo(o.y);
			
			return result;
		}  
		
		public String toString()
		{
			return x+" "+y;
		}
		
		public boolean equals(Object o)
		{
			if (o instanceof pair)
		    {
				pair p = (pair)o;
				return p.x == x && p.y == y ;
			}
			return false;
		}
		
		public int hashCode()
		{
			return new Long(x).hashCode()*31 + new Long(y).hashCode();
		}
	}
}