#include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
//#include <regex>

/* g++ -g -std=c++0x */
/* g++ -g -std=c++11 */

using namespace std;

// freopen("input.txt", "rt", stdin);
// freopen("output.txt", "wt", stdout);

#define ALL(c)          (c).begin(), (c).end()
#define ALLR(c)         (c).rbegin(), (c).rend()
#define FOR(i,a,b)      for (int i=(a); i < (b); ++i)
#define FORR(i,a,b)     for (int i=(a); i > (b); --i)
#define FOR_ALL(i,c)    for (__typeof((c).begin()) i=(c).begin();   \
                             i != (c).end(); ++i)
#define FOR_ALLR(i,c)   for (__typeof((c).rbegin()) i=(c).rbegin(); \
                             i != (c).rend(); ++i)
#define SZ(array)       (sizeof(array)/sizeof(array[0]))
#define lc(x)           (x<<1)     /* 2*x */
#define rc(x)           (x<<1 | 1) /* 2*x+1 */
#define lowbit(x)       (x & (-x)) /* 0b10100 -> 0b100 */

typedef long long       LL;
typedef map<int,int>    MII;
typedef pair<int,int>   PII;
typedef set<int>        SI;
typedef vector<bool>    VB;
typedef vector<double>  VD;
typedef vector<int>     VI;
typedef vector<string>  VS;

/* check if a key is in container C */
template <class C>
inline bool in_(const typename C::key_type& k, const C& A)
{ return A.find(k) != A.end(); }
inline bool in_(const string& s, const string& S)
{ return S.find(s) != string::npos; }


int main()
{
/* #ifndef ONLINE_JUDGE */
/*     freopen("foo", "rt", stdin); */
/* #endif */
    std::ios::sync_with_stdio(false);

    int C[3][3];
    int sum = 0;
    FOR(i,1,3+1) FOR(j,1,3+1) {
        cin >> C[i][j];
        sum += C[i][j];
    }
    bool good = false;
    if (sum % 3 == 0) {
        good = true;
        const int AB = sum/3;
        const int s1b = C[1][1] + C[1][2] + C[1][3];
        const int s2b = C[2][1] + C[2][2] + C[2][3];
        const int s3b = C[3][1] + C[3][2] + C[3][3];
        const int sa1 = C[1][1] + C[2][1] + C[3][1];
        const int sa2 = C[1][2] + C[2][2] + C[3][2];
        const int sa3 = C[1][3] + C[2][3] + C[3][3];
        {
            const int x = s1b+sa1 - AB;
            good &= (x%3 == 0 && x/3 == C[1][1]);
        }
        {
            const int x = s1b+sa2 - AB;
            good &= (x%3 == 0 && x/3 == C[1][2]);
        }

        {
            const int x = s1b+sa3 - AB;
            good &= (x%3 == 0 && x/3 == C[1][3]);
        }

        {
            const int x = s2b+sa1 - AB;
            good &= (x%3 == 0 && x/3 == C[2][1]);
        }
        {
            const int x = s2b+sa2 - AB;
            good &= (x%3 == 0 && x/3 == C[2][2]);
        }
        {
            const int x = s2b+sa3 - AB;
            good &= (x%3 == 0 && x/3 == C[2][3]);
        }
        {
            const int x = s3b+sa1 - AB;
            good &= (x%3 == 0 && x/3 == C[3][1]);
        }
        {
            const int x = s3b+sa2 - AB;
            good &= (x%3 == 0 && x/3 == C[3][2]);
        }
        {
            const int x = s3b+sa3 - AB;
            good &= (x%3 == 0 && x/3 == C[3][3]);
        }
    }
    if (good)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
    return 0;
}


Measured memory_bytes: 256