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

public class Main {

	final static long MOD = 1000000007L;
	public static String[] Ws = null;
	public static int wsIndx = 0;
	public static BufferedReader in = null;
	public static ArrayList<int[]> list = new ArrayList<>();
	public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	}


	public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	}

	public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	}
	public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	}

	public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	}

	public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	}

	public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	}


} import java.io.*; io.* java import java.util.*; util.* java public class Main {

	final static long MOD = 1000000007L;
	public static String[] Ws = null;
	public static int wsIndx = 0;
	public static BufferedReader in = null;
	public static ArrayList<int[]> list = new ArrayList<>();
	public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	}


	public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	}

	public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	}
	public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	}

	public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	}

	public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	}

	public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	}


} Main final static long MOD = 1000000007L; MOD 1000000007L public static String[] Ws = null; Ws null public static int wsIndx = 0; wsIndx 0 public static BufferedReader in = null; in null public static ArrayList<int[]> list = new ArrayList<>(); list new ArrayList<>() public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	} main {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	} int[][] c = new int[3][]; c new int[3][] 3 for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		} int i=0; int i=0; i 0 i<c.length i c.length c c.length i++ i++ i {
			c[i] = nextInts();
		} {
			c[i] = nextInts();
		} c[i] = nextInts() c[i] c i nextInts() nextInts int[] a = new int[3]; a new int[3] 3 int[] b = new int[3]; b new int[3] 3 a[0]=0 a[0] a 0 0 b[0]=c[0][0] b[0] b 0 c[0][0] c[0] c 0 0 b[1]=c[0][1] b[1] b 1 c[0][1] c[0] c 0 1 b[2]=c[0][2] b[2] b 2 c[0][2] c[0] c 0 2 a[1]=c[1][0]-b[0] a[1] a 1 c[1][0]-b[0] c[1][0] c[1] c 1 0 b[0] b 0 a[2]=c[2][0]-b[0] a[2] a 2 c[2][0]-b[0] c[2][0] c[2] c 2 0 b[0] b 0 String ans = "Yes"; ans "Yes" int sum=0; sum 0 for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		} int i=0; int i=0; i 0 i<3 i 3 i++ i++ i {
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		} {
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		} for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			} int k=0; int k=0; k 0 k<3 k 3 k++ k++ k {
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			} {
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			} if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				} c[i][k]!=a[i]+b[k] c[i][k] c[i] c i k a[i]+b[k] a[i] a i b[k] b k {
					ans="No";
					System.out.println(ans);
					return ;
				} ans="No" ans "No" System.out.println(ans) System.out.println System.out System System.out ans return ; System.out.println(ans) System.out.println System.out System System.out ans String[] args args public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	} toStringArray {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	} String[] tmp = new String[s.length()]; tmp new String[s.length()] s.length() s.length s char[] c = s.toCharArray(); c s.toCharArray() s.toCharArray s for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		} int i = 0; int i = 0; i 0 i < tmp.length i tmp.length tmp tmp.length i++ i++ i {
			tmp[i] = String.valueOf(c[i]);
		} {
			tmp[i] = String.valueOf(c[i]);
		} tmp[i] = String.valueOf(c[i]) tmp[i] tmp i String.valueOf(c[i]) String.valueOf String c[i] c i return tmp; tmp String s s public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	} check {
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	} if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		} in == null in null {
			in = new BufferedReader(new InputStreamReader(System.in));
		} in = new BufferedReader(new InputStreamReader(System.in)) in new BufferedReader(new InputStreamReader(System.in)) if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		} Ws==null || Ws.length<=wsIndx Ws==null Ws null Ws.length<=wsIndx Ws.length Ws Ws.length wsIndx {
			Ws = in.readLine().split(" ");
			wsIndx=0;
		} Ws = in.readLine().split(" ") Ws in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " wsIndx=0 wsIndx 0 public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	} nextInt {
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	} check() check return Integer.parseInt(Ws[wsIndx++]); Integer.parseInt(Ws[wsIndx++]) Integer.parseInt Integer Ws[wsIndx++] Ws wsIndx++ wsIndx public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	} nextLong {
		check();
		return Long.parseLong(Ws[wsIndx++]);
	} check() check return Long.parseLong(Ws[wsIndx++]); Long.parseLong(Ws[wsIndx++]) Long.parseLong Long Ws[wsIndx++] Ws wsIndx++ wsIndx public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	} nextString {
		check();
		return Ws[wsIndx++];
	} check() check return Ws[wsIndx++]; Ws[wsIndx++] Ws wsIndx++ wsIndx public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	} nextInts {
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	} check() check int[] tmp = new int[Ws.length]; tmp new int[Ws.length] Ws.length Ws Ws.length for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		} int i=0; int i=0; i 0 i<tmp.length i tmp.length tmp tmp.length i++ i++ i {
			tmp[i]=Integer.parseInt(Ws[i]);
		} {
			tmp[i]=Integer.parseInt(Ws[i]);
		} tmp[i]=Integer.parseInt(Ws[i]) tmp[i] tmp i Integer.parseInt(Ws[i]) Integer.parseInt Integer Ws[i] Ws i wsIndx=Ws.length wsIndx Ws.length Ws Ws.length return tmp; tmp public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	} nextLongs {
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	} check() check long[] tmp = new long[Ws.length]; tmp new long[Ws.length] Ws.length Ws Ws.length for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		} int i=0; int i=0; i 0 i<tmp.length i tmp.length tmp tmp.length i++ i++ i {
			tmp[i]=Long.parseLong(Ws[i]);
		} {
			tmp[i]=Long.parseLong(Ws[i]);
		} tmp[i]=Long.parseLong(Ws[i]) tmp[i] tmp i Long.parseLong(Ws[i]) Long.parseLong Long Ws[i] Ws i wsIndx=Ws.length wsIndx Ws.length Ws Ws.length return tmp; tmp public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	} nextStrings {
		check();
		wsIndx=Ws.length;
		return Ws;
	} check() check wsIndx=Ws.length wsIndx Ws.length Ws Ws.length return Ws; Ws public class Main {

	final static long MOD = 1000000007L;
	public static String[] Ws = null;
	public static int wsIndx = 0;
	public static BufferedReader in = null;
	public static ArrayList<int[]> list = new ArrayList<>();
	public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	}


	public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	}

	public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	}
	public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	}

	public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	}

	public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	}

	public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	}


} public class Main {

	final static long MOD = 1000000007L;
	public static String[] Ws = null;
	public static int wsIndx = 0;
	public static BufferedReader in = null;
	public static ArrayList<int[]> list = new ArrayList<>();
	public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	}


	public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	}

	public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	}
	public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	}

	public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	}

	public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	}

	public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	}


} Main
import java.io.*;
import java.util.*;

public class Main {

	final static long MOD = 1000000007L;
	public static String[] Ws = null;
	public static int wsIndx = 0;
	public static BufferedReader in = null;
	public static ArrayList<int[]> list = new ArrayList<>();
	public static void main(String[] args) throws Exception {

		int[][] c = new int[3][];

		for(int i=0;i<c.length;i++){
			c[i] = nextInts();
		}
		int[] a = new int[3];
		int[] b = new int[3];

		a[0]=0;
		b[0]=c[0][0];
		b[1]=c[0][1];
		b[2]=c[0][2];
		a[1]=c[1][0]-b[0];
		a[2]=c[2][0]-b[0];

		String ans = "Yes";
		int sum=0;
		for(int i=0;i<3;i++){
			for(int k=0;k<3;k++){
				if(c[i][k]!=a[i]+b[k]){
					ans="No";
					System.out.println(ans);
					return ;
				}
			}
		}
		System.out.println(ans);


	}


	public static String[] toStringArray(String s) {
		String[] tmp = new String[s.length()];
		char[] c = s.toCharArray();
		for (int i = 0; i < tmp.length; i++) {
			tmp[i] = String.valueOf(c[i]);
		}
		return tmp;
	}

	public static void check() throws Exception{
		if(in == null){
			in = new BufferedReader(new InputStreamReader(System.in));
		}
		if(Ws==null || Ws.length<=wsIndx){
			Ws = in.readLine().split(" ");
			wsIndx=0;
		}
	}
	public static int nextInt()throws Exception{
		check();
		return Integer.parseInt(Ws[wsIndx++]);
	}

	public static long nextLong()throws Exception{
		check();
		return Long.parseLong(Ws[wsIndx++]);
	}

	public static String nextString()throws Exception{
		check();
		return Ws[wsIndx++];
	}

	public static int[] nextInts()throws Exception{
		check();
		int[] tmp = new int[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Integer.parseInt(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static long[] nextLongs()throws Exception{
		check();
		long[] tmp = new long[Ws.length];
		for(int i=0;i<tmp.length;i++){
			tmp[i]=Long.parseLong(Ws[i]);
		}
		wsIndx=Ws.length;
		return tmp;
	}

	public static String[] nextStrings()throws Exception{
		check();
		wsIndx=Ws.length;
		return Ws;
	}


}
