import java.util.*;
import static java.lang.System.*;

class Main {
  public static final int MOD = 1000000007;
  public static final int INF = 1000000000;
  public static void main(String[] args) {
    Scanner sc = new Scanner(in);
    Integer c[][] = new Integer[3][3];
    for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    }
    int a,b;
    a = c[0][0] - c[0][1];
    b = c[0][1] - c[0][2];
    String ans = "Yes";
    for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    }
    for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    }
    out.println(ans);
          
  }

  public static int gcd(int a, int b){
    if(b == 0) return a;
    return gcd(b, a%b);
  }
} import java.util.*; util.* java import static java.lang.System.*; import static java.lang.System.*; import static java.lang.System.*; class Main {
  public static final int MOD = 1000000007;
  public static final int INF = 1000000000;
  public static void main(String[] args) {
    Scanner sc = new Scanner(in);
    Integer c[][] = new Integer[3][3];
    for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    }
    int a,b;
    a = c[0][0] - c[0][1];
    b = c[0][1] - c[0][2];
    String ans = "Yes";
    for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    }
    for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    }
    out.println(ans);
          
  }

  public static int gcd(int a, int b){
    if(b == 0) return a;
    return gcd(b, a%b);
  }
} Main public static final int MOD = 1000000007; MOD 1000000007 public static final int INF = 1000000000; INF 1000000000 public static void main(String[] args) {
    Scanner sc = new Scanner(in);
    Integer c[][] = new Integer[3][3];
    for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    }
    int a,b;
    a = c[0][0] - c[0][1];
    b = c[0][1] - c[0][2];
    String ans = "Yes";
    for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    }
    for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    }
    out.println(ans);
          
  } main {
    Scanner sc = new Scanner(in);
    Integer c[][] = new Integer[3][3];
    for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    }
    int a,b;
    a = c[0][0] - c[0][1];
    b = c[0][1] - c[0][2];
    String ans = "Yes";
    for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    }
    for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    }
    out.println(ans);
          
  } Scanner sc = new Scanner(in); sc new Scanner(in) Integer c[][] = new Integer[3][3]; c new Integer[3][3] 3 3 for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[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++){
        c[i][j] = sc.nextInt();
      }
    } {
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    } for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      } int j=0; int j=0; j 0 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 a a b; b a = c[0][0] - c[0][1] a c[0][0] - c[0][1] c[0][0] c[0] c 0 0 c[0][1] c[0] c 0 1 b = c[0][1] - c[0][2] b c[0][1] - c[0][2] c[0][1] c[0] c 0 1 c[0][2] c[0] c 0 2 String ans = "Yes"; ans "Yes" for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    } int i=1; int i=1; i 1 i<3 i 3 i++ i++ i {
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    } {
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    } if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      } a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2] a != c[i][0] - c[i][1] a c[i][0] - c[i][1] c[i][0] c[i] c i 0 c[i][1] c[i] c i 1 b != c[i][1] - c[i][2] b c[i][1] - c[i][2] c[i][1] c[i] c i 1 c[i][2] c[i] c i 2 {
        ans = "No";
        break;
      } ans = "No" ans "No" break; for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    } int j=1; int j=1; j 1 j<3 j 3 j++ j++ j {
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    } {
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    } if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      } c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j] c[0][0] - c[1][0] != c[0][j] - c[1][j] c[0][0] - c[1][0] c[0][0] c[0] c 0 0 c[1][0] c[1] c 1 0 c[0][j] - c[1][j] c[0][j] c[0] c 0 j c[1][j] c[1] c 1 j c[1][0] - c[2][0] != c[1][j] - c[2][j] c[1][0] - c[2][0] c[1][0] c[1] c 1 0 c[2][0] c[2] c 2 0 c[1][j] - c[2][j] c[1][j] c[1] c 1 j c[2][j] c[2] c 2 j {
        ans = "No";
        break;
      } ans = "No" ans "No" break; out.println(ans) out.println out ans String[] args args public static int gcd(int a, int b){
    if(b == 0) return a;
    return gcd(b, a%b);
  } gcd {
    if(b == 0) return a;
    return gcd(b, a%b);
  } if(b == 0) return a; b == 0 b 0 return a; a return gcd(b, a%b); gcd(b, a%b) gcd b a%b a b int a a int b b
import java.util.*;
import static java.lang.System.*;

class Main {
  public static final int MOD = 1000000007;
  public static final int INF = 1000000000;
  public static void main(String[] args) {
    Scanner sc = new Scanner(in);
    Integer c[][] = new Integer[3][3];
    for(int i=0; i<3; i++){
      for(int j=0; j<3; j++){
        c[i][j] = sc.nextInt();
      }
    }
    int a,b;
    a = c[0][0] - c[0][1];
    b = c[0][1] - c[0][2];
    String ans = "Yes";
    for(int i=1; i<3; i++){
      if(a != c[i][0] - c[i][1] || b != c[i][1] - c[i][2]){
        ans = "No";
        break;
      }
    }
    for(int j=1; j<3; j++){
      if(c[0][0] - c[1][0] != c[0][j] - c[1][j] || c[1][0] - c[2][0] != c[1][j] - c[2][j]){
        ans = "No";
        break;
      }
    }
    out.println(ans);
          
  }

  public static int gcd(int a, int b){
    if(b == 0) return a;
    return gcd(b, a%b);
  }
}