import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
long bignum = 1_000_000_007;

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    auto c = new long[](0);
    foreach (_; 0 .. 3)
    {
        auto tmp = aryread();
        c ~= tmp;
    }
    bool check = true;
    long b1, b2, b3, a2, a3;
    b1 = c[0];
    b2 = c[1];
    b3 = c[2];
    if(!((c[3] - b1) == (c[4] - b2) && (c[3] - b1) == (c[5] - b3)))
        check = false;
    if(!((c[6] - b1) == (c[7] - b2) && (c[6] - b1) == (c[8] - b3)))
        check = false;

    if(check)
        writeln("Yes");
    else
        writeln("No");
}