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
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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
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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
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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
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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
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0 9 5 7 6 2
8 6 2 7 1 4
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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
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1 3 4 6 7 0
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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
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0 1 2 3 4 5
0 1 2 3 4 5
0 1 2 3 4 5
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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
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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
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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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0 1 2 3 4 5
6 7 8 9 1 2
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5 3 8 0 2 6
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0 7 6 3 2 4
 2
8 0 6 5 1 4
7 1 0 8 3 4
 2
7 8 6 1 4 5
8 6 4 3 2 5
 2
0 1 2 3 4 5
6 6 6 7 8 9
 3
9 3 1 8 4 6
6 9 1 2 0 7
8 9 1 5 0 3
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0 6 2 9 5 4
3 8 0 1 6 9
6 9 0 1 5 2
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0 1 2 2 4 5
6 7 8 9 0 1
3 3 4 5 6 7
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8 6 4 1 2 0
7 8 5 3 2 1
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5 6 2 9 3 5
5 4 1 5 9 8
4 4 2 0 3 5
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7 2 1 3 6 9
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
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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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6 0 7 5 4 8
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5 8 4 7 1 2
0 8 6 2 4 9
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5 2 2 5 6 7
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6 5 2 7 1 3
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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2 3 4 5 6 7
3 4 5 6 7 8
9 1 2 3 4 5
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0 1 2 3 4 5
4 5 6 7 8 9
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2 7 3 6 4 5
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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0 9 3 5 8 6
2 4 7 8 1 3
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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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3 4 5 6 6 7
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7 1 6 9 5 4
5 0 4 0 3 9
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0 7 4 3 2 5
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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 0 0 6 4 4
1 2 1 1 9 1
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2 4 3 0 9 5
1 9 8 0 6 5
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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.util.*;
import java.io.*;
public class codeforces{
	static class InputReader {
		public BufferedReader reader;
		public StringTokenizer tokenizer;
		public InputReader() {
			reader = new BufferedReader(new InputStreamReader(System.in));
			tokenizer = null;
		}
 
		public String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}
 
		public int nextInt() {
			return Integer.parseInt(next());
		}
 
		public long nextLong() {
			return Long.parseLong(next());
		}
 
		public double nextDouble() {
			return Double.parseDouble(next());
		}
 
		public String nextLine() {
			String s = null;
			try {
				s = reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			return s;
		}
 
		public String nextParagraph() {
			String line = null;
			String ans = "";
			try {
				while ((line = reader.readLine()) != null) {
					ans += line;
				}
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			return ans;
		}
	}
	//static int mod = 1000000007;
	static void printArray(int ar[]){
		for(int x:ar)
			System.out.print(x+" ");
	}
	static void printMatrix(int ar[][],int n){
		for(int i=0;i<n;i++){
			for(int j=i;j<n;j++){
				System.out.print(ar[i][j]+" ");
			}
			System.out.println();
		}
	}
	static class Data{
		int t;
		int l;
		int r;
		public Data(int t,int l,int r){
			this.t=t;
			this.l=l;
			this.r=r;
		}
	}
	static int gcd(int a, int b){
	    if (a == 0)
	        return b;
	    return gcd(b%a, a);
	}
 	static void createNums(int cubeN[],int ar[],int c[],int num,int len){;
 		for(int i=0;i<len;i++){
 			if(cubeN[i]==-1){
 				cubeN[i]=1;
 				for(int j=6*i;j<6*(i+1);j++){
 					int n=num*10+c[j];
 					ar[n]=1;
 					createNums(cubeN,ar,c,n,len);	
 				}
 				cubeN[i]=-1;
 			}
 		}	
 	}
	public static void main(String args[]){
		InputReader sc=new InputReader();
		PrintWriter pw=new PrintWriter(System.out);
		int n=sc.nextInt();
		int c[]=new int[18];
		int ar[]=new int[1000];
		int i=0;
		Arrays.fill(ar,-1);
		for(i=0;i<n;i++){
			for(int j=0;j<6;j++)
				c[6*i+j]=sc.nextInt();
		}
		for(i=0;i<n;i++){
			int cubeN[]=new int[n];
			Arrays.fill(cubeN,-1);
			for(int j=6*i;j<6*i+6;j++){
				int num = c[j];
				ar[num]=1;
				cubeN[i]=1;
				createNums(cubeN,ar,c,num,n);
			}
		}
		for(i=1;i<=999;i++){
			if(ar[i]==-1)
				break;
		}
		pw.println((i-1));
		pw.close();
	}
}   