import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    } main {
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[][] l = new int[3][3]; l new int[3][3] 3 3 for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt(); int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt(); for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt(); int j = 0; int j = 0; j 0 j < 3 j 3 j++ j++ j l[i][j] = sc.nextInt(); l[i][j] = sc.nextInt() l[i][j] l[i] l i j sc.nextInt() sc.nextInt sc if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No"); l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2] l[1][0] + l[0][2] == l[0][0] + l[1][2] l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2] l[0][0] + l[1][1] == l[1][0] + l[0][1] l[0][0] + l[1][1] l[0][0] l[0] l 0 0 l[1][1] l[1] l 1 1 l[1][0] + l[0][1] l[1][0] l[1] l 1 0 l[0][1] l[0] l 0 1 l[0][0] + l[2][1] == l[2][0] + l[0][1] l[0][0] + l[2][1] l[0][0] l[0] l 0 0 l[2][1] l[2] l 2 1 l[2][0] + l[0][1] l[2][0] l[2] l 2 0 l[0][1] l[0] l 0 1 l[1][0] + l[0][2] == l[0][0] + l[1][2] l[1][0] + l[0][2] l[1][0] l[1] l 1 0 l[0][2] l[0] l 0 2 l[0][0] + l[1][2] l[0][0] l[0] l 0 0 l[1][2] l[1] l 1 2 l[0][0] + l[2][2] == l[2][0] + l[0][2] l[0][0] + l[2][2] l[0][0] l[0] l 0 0 l[2][2] l[2] l 2 2 l[2][0] + l[0][2] l[2][0] l[2] l 2 0 l[0][2] l[0] l 0 2 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    }
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int[][] l = new int[3][3];
        for(int i = 0;i < 3;i++)    for(int j = 0;j < 3;j++)    l[i][j] = sc.nextInt();
        if(l[0][0] + l[1][1] == l[1][0] + l[0][1] 
            && l[0][0] + l[2][1] == l[2][0] + l[0][1] 
                && l[1][0] + l[0][2] == l[0][0] + l[1][2]
                    && l[0][0] + l[2][2] == l[2][0] + l[0][2])  System.out.println("Yes");
        else    System.out.println("No");
    }
}