using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace NotFounds
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var sw = new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            Console.SetOut(sw);
            new Program().Solve(new ConsoleInput(Console.In, ' '));
            Console.Out.Flush();
        }

        public void Solve(ConsoleInput cin)
        {
            checked
            {
                var c = new int[3, 3];
                for (int i = 0; i < 3; ++i)
                    for (int j = 0; j < 3; ++j)
                        c[i, j] = cin.ReadInt;

                for (int a1 = 0; a1 <= 100; ++a1)
                {
                    var b1 = c[0, 0] - a1;
                    var b2 = c[0, 1] - a1;
                    var b3 = c[0, 2] - a1;
                    for (int a2 = 0; a2 <= 100; ++a2)
                    {
                        if (c[1, 0] - a2 != b1) continue;
                        if (c[1, 1] - a2 != b2) continue;
                        if (c[1, 2] - a2 != b3) continue;
                        for (int a3 = 0; a3 <= 100; ++a3)
                        {
                            if (c[2, 0] - a3 != b1) continue;
                            if (c[2, 1] - a3 != b2) continue;
                            if (c[2, 2] - a3 != b3) continue;
                            WriteLine("Yes");
                            return;
                        }
                    }
                }
                WriteLine("No");
            }
        }
    }

    public class ConsoleInput
    {
        private readonly System.IO.TextReader _stream;
        private char _separator = ' ';
        private Queue<string> inputStream;
        public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
        {
            this._separator = separator;
            this._stream = stream;
            inputStream = new Queue<string>();
        }
        public string Read
        {
            get
            {
                if (inputStream.Count != 0) return inputStream.Dequeue();
                string[] tmp = _stream.ReadLine().Split(_separator);
                for (int i = 0; i < tmp.Length; ++i)
                    inputStream.Enqueue(tmp[i]);
                return inputStream.Dequeue();
            }
        }
        public string ReadLine { get { return _stream.ReadLine(); }}
        public int ReadInt { get { return int.Parse(Read); }}
        public long ReadLong { get { return long.Parse(Read); }}
        public double ReadDouble { get { return double.Parse(Read); }}
        public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret;}
        public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret;}
        public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret;}
        public void ReadIntArrays(long N, out int[] A, out int[] B) { A = new int[N]; B = new int[N]; for (long i = 0; i < N; ++i) { A[i] = ReadInt; B[i] = ReadInt; }}
        public void ReadIntArrays(long N, out int[] A, out int[] B, out int[] C) { A = new int[N]; B = new int[N]; C = new int[N]; for (long i = 0; i < N; ++i) { A[i] = ReadInt; B[i] = ReadInt; C[i] = ReadInt; }}
        public void ReadLongArrays(long N, out long[] A, out long[] B) { A = new long[N]; B = new long[N]; for (long i = 0; i < N; ++i) { A[i] = ReadLong; B[i] = ReadLong; }}
    }
}


Measured memory_bytes: 13268