import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int c[][] = new int[3][3];
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int x[] = new int[3];
    int y[] = new int[3];
    x[0] = 0;
    for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0];
    for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0];

    boolean flag = true;
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    }
    System.out.println(flag ? "Yes" : "No");
  }
} import java.util.*; util.* java class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int c[][] = new int[3][3];
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int x[] = new int[3];
    int y[] = new int[3];
    x[0] = 0;
    for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0];
    for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0];

    boolean flag = true;
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    }
    System.out.println(flag ? "Yes" : "No");
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int c[][] = new int[3][3];
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int x[] = new int[3];
    int y[] = new int[3];
    x[0] = 0;
    for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0];
    for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0];

    boolean flag = true;
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    }
    System.out.println(flag ? "Yes" : "No");
  } main {
    Scanner sc = new Scanner(System.in);
    int c[][] = new int[3][3];
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int x[] = new int[3];
    int y[] = new int[3];
    x[0] = 0;
    for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0];
    for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0];

    boolean flag = true;
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    }
    System.out.println(flag ? "Yes" : "No");
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int c[][] = new int[3][3]; c new int[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 x[] = new int[3]; x new int[3] 3 int y[] = new int[3]; y new int[3] 3 x[0] = 0 x[0] x 0 0 for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0]; int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i y[i] = c[0][i] - x[0]; y[i] = c[0][i] - x[0] y[i] y i c[0][i] - x[0] c[0][i] c[0] c 0 i x[0] x 0 for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0]; int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i x[i] = c[i][0] - y[0]; x[i] = c[i][0] - y[0] x[i] x i c[i][0] - y[0] c[i][0] c[i] c i 0 y[0] y 0 boolean flag = true; flag true for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    } int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    } {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    } for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      } int j = 0; int j = 0; j 0 j < 3 j 3 j++ j++ j {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      } {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      } if (x[i] + y[j] != c[i][j])
          flag = false; x[i] + y[j] != c[i][j] x[i] + y[j] x[i] x i y[j] y j c[i][j] c[i] c i j flag = false flag false System.out.println(flag ? "Yes" : "No") System.out.println System.out System System.out flag ? "Yes" : "No" flag "Yes" "No" String[] args args
import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int c[][] = new int[3][3];
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        c[i][j] = sc.nextInt();
      }
    }
    int x[] = new int[3];
    int y[] = new int[3];
    x[0] = 0;
    for (int i = 0; i < 3; i++)
      y[i] = c[0][i] - x[0];
    for (int i = 0; i < 3; i++)
      x[i] = c[i][0] - y[0];

    boolean flag = true;
    for (int i = 0; i < 3; i++) {
      for (int j = 0; j < 3; j++) {
        if (x[i] + y[j] != c[i][j])
          flag = false;
      }
    }
    System.out.println(flag ? "Yes" : "No");
  }
}