2
2 6 8 1 3 1
2 1 3 8 6 7
 2
1 8 9 1 1 0
2 3 4 5 6 7
 2
0 2 9 8 1 7
6 7 4 3 2 5
 3
9 4 6 2 7 0
3 7 1 9 6 4
6 1 0 8 7 2
 3
2 7 4 0 7 1
5 5 4 9 1 4
2 1 7 5 1 7
 3
5 1 2 9 6 4
9 0 6 4 2 8
4 6 2 8 3 7
 3
1 1 1 0 2 3
4 5 6 7 8 9
0 0 0 0 0 0
 1
1 9 8 3 7 8
 3
2 6 3 7 1 0
9 1 2 4 7 6
1 4 8 7 6 2
 1
4 6 9 8 2 7
 2
1 7 6 9 2 5
1 6 7 0 9 2
 3
4 1 0 8 0 2
1 5 3 5 0 7
7 7 2 7 2 2
 1
7 6 5 8 9 0
 3
3 8 3 5 5 5
3 0 1 6 6 3
0 4 3 7 2 4
 1
8 1 9 2 9 7
 2
2 0 5 7 0 8
4 5 1 5 4 9
 3
1 1 1 1 1 1
0 2 3 4 5 6
7 8 9 2 3 4
 3
0 1 1 2 2 3
4 5 6 7 8 9
3 4 5 6 7 1
 1
0 8 7 1 3 2
 2
9 3 3 6 7 2
6 2 9 1 5 9
 1
8 2 7 4 1 0
 2
3 6 8 9 5 0
6 7 0 8 2 3
 1
0 1 2 3 4 5
 3
3 4 5 6 8 9
1 1 1 1 1 1
1 2 4 5 7 0
 2
2 3 5 1 9 6
1 6 8 7 3 9
 2
0 9 5 7 6 2
8 6 2 7 1 4
 2
4 3 8 6 0 1
4 7 1 8 9 0
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6 2 8 4 5 1
 1
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 2
6 0 1 7 2 9
1 3 4 6 7 0
 3
5 0 7 6 2 1
2 7 4 6 1 9
0 2 6 1 7 5
 3
0 1 1 2 2 3
4 5 6 7 8 9
3 4 5 6 7 8
 3
0 1 2 3 4 5
0 1 2 3 4 5
0 1 2 3 4 5
 2
2 4 0 3 7 6
3 2 8 7 1 5
 1
7 3 6 9 8 1
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1 1 2 3 4 5
6 7 8 9 0 2
3 4 5 6 7 8
 3
9 4 3 0 2 6
7 0 5 3 3 9
1 0 7 4 6 7
 1
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2 5 7 4 2 7
1 5 5 9 0 3
8 2 0 1 5 1
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1 7 8 6 0 9
3 2 1 7 4 9
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0 8 6 2 1 3
5 2 7 1 0 9
 2
5 3 2 9 8 2
0 7 4 8 1 8
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3 8 5 1 5 5
1 5 7 2 6 9
4 3 4 8 8 9
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5 1 2 3 0 8
3 6 7 4 9 2
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6 7 8 9 1 2
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5 3 8 0 2 6
 1
0 7 6 3 2 4
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8 0 6 5 1 4
7 1 0 8 3 4
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7 8 6 1 4 5
8 6 4 3 2 5
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0 1 2 3 4 5
6 6 6 7 8 9
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9 3 1 8 4 6
6 9 1 2 0 7
8 9 1 5 0 3
 3
0 6 2 9 5 4
3 8 0 1 6 9
6 9 0 1 5 2
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6 7 8 9 0 1
3 3 4 5 6 7
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7 8 5 3 2 1
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5 4 1 5 9 8
4 4 2 0 3 5
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0 3 8 4 7 6
1 4 5 8 7 0
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9 4 3 3 9 3
1 0 3 4 5 3
2 9 6 2 4 1
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1 2 3 7 8 9
9 8 7 1 2 3
7 9 2 3 1 8
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8 1 8 2 7 1
9 1 9 9 4 7
0 0 9 0 4 0
 1
2 5 9 6 7 9
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8 6 9 0 7 2
6 9 3 2 5 7
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1 8 5 3 9 7
7 4 5 1 6 8
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8 6 0 9 4 2
 1
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 1
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5 8 4 7 1 2
0 8 6 2 4 9
 1
5 2 2 5 6 7
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3 7 8 1 0 9
 1
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0 1 2 3 4 5
6 7 8 9 1 2
3 4 5 6 7 8
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6 6 4 7 9 0
2 1 2 8 6 4
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3 4 5 6 7 8
9 1 2 3 4 5
 2
0 1 2 3 4 5
4 5 6 7 8 9
 3
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0 2 1 9 4 8
8 6 9 5 4 0
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0 1 2 3 4 5
6 7 8 9 6 6
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5 2 3 6 1 0
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6 2 8 5 1 3
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5 4 8 1 6 7
0 9 3 5 8 6
2 4 7 8 1 3
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6 3 1 9 4 9
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0 1 9 1 0 8
9 9 3 5 6 2
9 3 9 9 7 3
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8 1 6 8 6 8
7 0 2 5 8 4
5 2 0 3 1 9
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6 7 8 9 1 1
3 4 5 6 6 7
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4 4 5 0 6 6
7 1 6 9 5 4
5 0 4 0 3 9
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0 1 2 3 4 5
9 8 7 6 5 4
 2
0 2 9 1 8 5
0 7 4 3 2 5
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2 3 9 1 6 7
2 5 4 3 0 6
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5 7 4 2 1 9
2 2 7 1 1 8
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3 9 1 7 4 5
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7 7 2 5 3 2
3 0 0 6 4 4
1 2 1 1 9 1
 1
7 9 5 0 4 6
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7 1 3 0 2 4
2 4 3 0 9 5
1 9 8 0 6 5
 1
4 3 8 9 2 3

3
 9
 9
 4
 2
 10
 10
 1
 4
 0
 2
 5
 0
 8
 2
 2
 10
 19
 3
 3
 2
 0
 5
 19
 3
 2
 1
 2
 1
 4
 2
 9
 5
 8
 1
 10
 7
 0
 5
 4
 3
 5
 9
 9
 29
 0
 0
 1
 8
 9
 21
 6
 21
 1
 8
 6
 1
 21
 6
 3
 2
 0
 0
 1
 0
 0
 0
 2
 0
 3
 0
 98
 2
 9
 9
 10
 9
 7
 3
 21
 1
 3
 32
 19
 1
 9
 5
 7
 2
 1
 7
 0
 65
 0

import java.io.*;
import java.util.*;
import java.math.*;
import java.lang.*;
 
import static java.lang.Math.*;
 
public class Main implements Runnable
{
	static class InputReader
	{
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;
		private BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

		public InputReader(InputStream stream)
		{
			this.stream = stream;
		}
		
		public int read()
		{
			if (numChars==-1) 
				throw new InputMismatchException();
			
			if (curChar >= numChars)
			{
				curChar = 0;
				try 
				{
					numChars = stream.read(buf);
				}
				catch (IOException e)
				{
					throw new InputMismatchException();
				}
				
				if(numChars <= 0)				
					return -1;
			}
			return buf[curChar++];
		}
	 
		public String nextLine()
		{
			String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
		}
		public int nextInt()
		{
			int c = read();
			
			while(isSpaceChar(c)) 
				c = read();
			
			int sgn = 1;
			
			if (c == '-') 
			{
				sgn = -1;
				c = read();
			}
			
			int res = 0;
			do 
			{
				if(c<'0'||c>'9') 
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			while (!isSpaceChar(c)); 
			
			return res * sgn;
		}
		
		public long nextLong() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') 
			{
				sgn = -1;
				c = read();
			}
			long res = 0;
			
			do 
			{
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			while (!isSpaceChar(c));
				return res * sgn;
		}
		
		public double nextDouble() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') 
			{
				sgn = -1;
				c = read();
			}
			double res = 0;
			while (!isSpaceChar(c) && c != '.') 
			{
				if (c == 'e' || c == 'E')
					return res * Math.pow(10, nextInt());
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			}
			if (c == '.') 
			{
				c = read();
				double m = 1;
				while (!isSpaceChar(c)) 
				{
					if (c == 'e' || c == 'E')
						return res * Math.pow(10, nextInt());
					if (c < '0' || c > '9')
						throw new InputMismatchException();
					m /= 10;
					res += (c - '0') * m;
					c = read();
				}
			}
			return res * sgn;
		}
		
		public String readString() 
		{
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do 
			{
				res.appendCodePoint(c);
				c = read();
			} 
			while (!isSpaceChar(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;
		}
	 
		public String next() 
		{
			return readString();
		}
		
		public interface SpaceCharFilter 
		{
			public boolean isSpaceChar(int ch);
		}
	}
 	
	public static void main(String args[]) throws Exception
	{
		new Thread(null, new Main(),"Main",1<<26).start();
	}	
    void compute(ArrayList<Integer> list)
    {   
        if(list.size() == 1)
        {
            int cur = list.get(0);
            for(int i = 0; i < 6; ++i)
                map.put(cube[cur][i], 1);
        }
        else if(list.size() == 2)
        {
            int cur = list.get(0);
            int cur2 = list.get(1);
            for(int i = 0; i < 6; ++i)
            {
                int num = cube[cur][i];
                if(num == 0)
                    continue;
                for(int j = 0; j < 6; ++j)
                    map.put(num * 10 + cube[cur2][j], 1);
            }
        }
        else
        {
            int cur = list.get(0);
            int cur2 = list.get(1);
            int cur3 = list.get(2);
            for(int i = 0; i < 6; ++i)
            {
                int num = cube[cur][i];
                if(num == 0)
                    continue;
                for(int j = 0; j < 6; ++j)
                {
                    int num2 = num * 10 + cube[cur2][j];
                    for(int k = 0; k < 6; ++k)
                        map.put(num2 * 10 + cube[cur3][k], 1);
                }
            }
        }
    }
    void permute(int len, int max, ArrayList<Integer> list)
    {
        if(len == max)
        {
            compute(list);
            return;
        }
        //System.out.print(n);
        for(int i = 0; i < n; ++i)
        {
            if(visited[i] == 0)
            {
                visited[i] = 1;
                list.add(i);
                permute(len + 1, max, list);
                list.remove(list.size() - 1);
                visited[i] = 0;
            }
        }
    }
    int cube[][];
    HashMap<Integer, Integer> map = new HashMap<>();
    int visited[], n;
	public void run()
	{
		InputReader sc = new InputReader(System.in);
		PrintWriter w = new PrintWriter(System.out);
        
        n = sc.nextInt();
        cube = new int[n][6];
        
        for(int i = 0; i < n; ++i)
            for(int j = 0; j < 6; ++j)
                cube[i][j] = sc.nextInt();
        
        for(int i = 1; i <= n; ++i)
        {
            visited = new int[n];
            permute(0, i, new ArrayList<Integer>());
        }
		
        int ans = -1;
        
        for(int i = 1; i <= 1000000; ++i)
        {
            if(map.get(i) == null)
            {
                ans = i - 1;
                break;
            }
        }
        
        w.print(ans);
        
		w.close();
	}
}