import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  } main {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[][] c = new int[4][4]; c new int[4][4] 4 4 for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    } int i = 1; int i = 1; i 1 i <= 3 i 3 i++ i++ i {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    } {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    } for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      } int j = 1; int j = 1; j 1 j <= 3 j 3 j++ j++ j {
        c[i][j] = sc.nextInt();
      } {
        c[i][j] = sc.nextInt();
      } c[i][j] = sc.nextInt() c[i][j] c[i] c i j sc.nextInt() sc.nextInt sc int a1 = 0; a1 0 int b1 = c[1][1] - a1; b1 c[1][1] - a1 c[1][1] c[1] c 1 1 a1 int b2 = c[1][2] - a1; b2 c[1][2] - a1 c[1][2] c[1] c 1 2 a1 int b3 = c[1][3] - a1; b3 c[1][3] - a1 c[1][3] c[1] c 1 3 a1 boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3; ans c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3 c[3][1] - b1 == c[3][2] - b2 c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3 c[2][1] - b1 == c[2][2] - b2 c[2][1] - b1 c[2][1] c[2] c 2 1 b1 c[2][2] - b2 c[2][2] c[2] c 2 2 b2 c[2][2] - b2 == c[2][3] - b3 c[2][2] - b2 c[2][2] c[2] c 2 2 b2 c[2][3] - b3 c[2][3] c[2] c 2 3 b3 c[3][1] - b1 == c[3][2] - b2 c[3][1] - b1 c[3][1] c[3] c 3 1 b1 c[3][2] - b2 c[3][2] c[3] c 3 2 b2 c[3][2] - b2 == c[3][3] - b3 c[3][2] - b2 c[3][2] c[3] c 3 2 b2 c[3][3] - b3 c[3][3] c[3] c 3 3 b3 System.out.println(ans ? "Yes" : "No") System.out.println System.out System System.out ans ? "Yes" : "No" ans "Yes" "No" String[] args args public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  }
} Main
import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] c = new int[4][4];
    for (int i = 1; i <= 3; i++) {
      for (int j = 1; j <= 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int a1 = 0;
    int b1 = c[1][1] - a1;
    int b2 = c[1][2] - a1;
    int b3 = c[1][3] - a1;
    
    boolean ans = 
         c[2][1] - b1 == c[2][2] - b2
      && c[2][2] - b2 == c[2][3] - b3
      && c[3][1] - b1 == c[3][2] - b2
      && c[3][2] - b2 == c[3][3] - b3;
    
    System.out.println(ans ? "Yes" : "No");
  }
}