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

public class Solution{
    public static void main(String args[]){
        Scanner sc=new Scanner(System.in);
        int[][] magic=new int[3][3];
        int[] count={0,0,0,0,0,0,0,0,0,0};
        int change=0;
        int missing=0;
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                magic[i][j]=sc.nextInt();
               // System.out.println(magic[i][j]);
            }
        }
        for(int x=0;x<3;x++){
            for(int y=0;y<3;y++){
                if(magic[x][y]==1){
                    count[1]++;
                }else if(magic[x][y]==2){
                    count[2]++;
                }else if(magic[x][y]==3){
                    count[3]++;
                }else if(magic[x][y]==4){
                    count[4]++;
                }else if(magic[x][y]==5){
                    count[5]++;
                }else if(magic[x][y]==6){
                    count[6]++;
                }
                else if(magic[x][y]==7){
                    count[7]++;
                }else if(magic[x][y]==8){
                    count[8]++;
                }else if(magic[x][y]==9){
                    count[9]++;
                }
                
            }
        }
            for(int s=1;s<10;s++){
                if(count[s]>1){
                    change=s;
                }
                if(count[s]==0){
                    missing=s;
                }
            }
            for(int a=0;a<3;a++){
                for(int b=0;b<3;b++){
                    if(magic[a][b]==change){
                        if(a>0 & b>0){
                            if((magic[a-1][b-1]+magic[a][b]+magic[a+1][b+1])==(magic[a-1][b+1]+magic[a][b]+magic[a+1][b-1])){
                                //do nothing
                            }else{
                                magic[a][b]=missing;
                                System.out.println(Math.abs(change-missing));
                            }
                        }
                    }
                }
            }
            
        
    }
}