#include <bits/stdc++.h>
                                    #include<iostream>
                                    #include<cstdio>
                                    #include<vector>
                                    #include<queue>
                                    #include<map>
                                    #include<cstring>
                                    #include<string>
                                    #include <math.h>
                                    #include<algorithm>
                                //    #include <boost/multiprecision/cpp_int.hpp>
                                    #include<functional>
                        //  #define int long long
                                    #define inf  1000000007
                                    #define pa pair<int,int>
                                    #define ll long long
                                    #define pal pair<double,pa>
                                    #define ppa pair<pa,int>
                                    #define ppap pair<int,pa>
                                    #define ssa pair<string,int>
                                    #define  mp make_pair
                                    #define  pb push_back
                                    #define EPS (1e-10)
                                    #define equals(a,b) (fabs((a)-(b))<EPS)
                             
                                    using namespace std;
                          
                                    class Point{
                                    	public:
                                    	double x,y;
                                    	Point(double x=0,double y=0):x(x),y(y) {}
                                    	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
                                    	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
                                    	Point operator * (double a) {return Point(x*a,y*a);}
                                    	Point operator / (double a) {return Point(x/a,y/a);}
                                    	double absv() {return sqrt(norm());}
                                    	double norm() {return x*x+y*y;}
                                    	bool operator < (const Point &p) const{
                                    		return x != p.x ? x<p.x: y<p.y;
                                    	}
                                    	bool operator == (const Point &p) const{
                                    		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
                                    	}
                                    };
                                    typedef Point Vector;
                             
                                    struct Segment{
                                    Point p1,p2;
                                    };
                                     double dot(Vector a,Vector b){
                                    	return a.x*b.x+a.y*b.y;
                                    }
                                    double cross(Vector a,Vector b){
                                    	return a.x*b.y-a.y*b.x;
                                    }
                                    class pa3{
                                        	public:
                                        	int x,y,z;
                                        	pa3(int x=0,int y=0,int z=0):x(x),y(y),z(z) {}
                                        	bool operator < (const pa3 &p) const{
                                        		if(x!=p.x) return x<p.x;
                                        		if(y!=p.y) return y<p.y;
                                        		 return z<p.z;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                               				bool operator > (const pa3 &p) const{
                                        		if(x!=p.x) return x>p.x;
                                        		if(y!=p.y) return y>p.y;
                                        		 return z>p.z;
                                        		//return x != p.x ? x<p.x: y<p.y;
                                        	}
                                        	bool operator == (const pa3 &p) const{
                                        		return x==p.x && y==p.y && z==p.z;
                                        	}
                                        		bool operator != (const pa3 &p) const{
                                        			return !( x==p.x && y==p.y && z==p.z);
                                        	}
                                        
                                        };
                                        
                                
        bool parareru(Point a,Point b,Point c,Point d){
        //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
        	return abs(cross(a-b,d-c))<EPS;
        }
        double distance_ls_p(Point a, Point b, Point c) {
          if ( dot(b-a, c-a) < EPS ) return (c-a).absv();
          if ( dot(a-b, c-b) < EPS ) return (c-b).absv();
          return abs(cross(b-a, c-a)) / (b-a).absv();
        }
        bool is_intersected_ls(Segment a,Segment b) {
        	if(a.p1==b.p1||a.p2==b.p1||a.p1==b.p2||a.p2==b.p2) return false;
        	if(parareru((a.p2),(a.p1),(a.p1),(b.p2))&&parareru((a.p2),(a.p1),(a.p1),(b.p1))){
        //		cout<<"sss"<<endl;
        		if(dot(a.p1-b.p1,a.p1-b.p2)<EPS) return true;
        		if(dot(a.p2-b.p1,a.p2-b.p2)<EPS) return true;
        		if(dot(a.p1-b.p1,a.p2-b.p1)<EPS) return true;
        		if(dot(a.p1-b.p2,a.p2-b.p2)<EPS) return true;
        		return false;
        	}
          else return ( cross(a.p2-a.p1, b.p1-a.p1) * cross(a.p2-a.p1, b.p2-a.p1) < EPS ) && ( cross(b.p2-b.p1, a.p1-b.p1) * cross(b.p2-b.p1, a.p2-b.p1) < EPS );
        }
         
        double segment_dis(Segment a,Segment b){
        	if(is_intersected_ls(a,b))return 0;
        	double r=distance_ls_p(a.p1, a.p2, b.p1);
        	r=min(r,distance_ls_p(a.p1, a.p2, b.p2));
        	r=min(r,distance_ls_p(b.p1, b.p2, a.p2));
        	r=min(r,distance_ls_p(b.p1, b.p2, a.p1));
        	return r;
        }
        Point intersection_ls(Segment a, Segment b) {
          Point ba = b.p2-b.p1;
          double d1 = abs(cross(ba, a.p1-b.p1));
          double d2 = abs(cross(ba, a.p2-b.p1));
          double t = d1 / (d1 + d2);
         
          return a.p1 + (a.p2-a.p1) * t;
        }
         
                        string itos( int i ) {
                        ostringstream s ;
                        s << i ;
                        return s.str() ;
                        }
                         
                        int gcd(int v,int b){
                        	if(v>b) return gcd(b,v);
                        	if(v==b) return b;
                        	if(b%v==0) return v;
                        	return gcd(v,b%v);
                        }
         
                        double distans(double x1,double y1,double x2,double y2){
                        	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
                        	return sqrt(rr);
                        	
                        }
                        /*
        int pr[100010];
        //int inv[100010];
        */ 
        int beki(int wa,int rr,int warukazu){
        	if(rr==0) return 1ll;
        	if(rr==1) return wa%warukazu;
        	if(rr%2==1) return (beki(wa,rr-1,warukazu)*wa)%warukazu;
        	int zx=beki(wa,rr/2,warukazu);
        	return (zx*zx)%warukazu;
        }
          /*
        void gya(){
        	pr[0]=1;
        	for(int i=1;i<100010;i++){
        		pr[i]=(pr[i-1]*i)%inf;
        	}
        	for(int i=0;i<100010;i++) inv[i]=beki(pr[i],inf-2);
        	
        }
         
        */
         //sort(ve.begin(),ve.end(),greater<int>());
                                 //----------------kokomade tenpure------------
        //vector<double> ans(100000000),ans2(100000000);
        /*
        int par[200100],ranks[200100],kosuu[200100];     
         
        void shoki(int n){
        	for(int i=0;i<n;i++){
        		par[i]=i;
        		ranks[i]=0;
        		kosuu[i]=1;
        	}
        }
         
        int root(int x){
        	return par[x]==x ? x : par[x]=root(par[x]);
        }
         
        bool same(int x,int y){
        return root(x)==root(y);
        }
         
        void unite(int x,int y){
         x=root(x);
         y=root(y);
        	int xx=kosuu[x],yy=kosuu[y];
         if(x==y) return;
        	if(ranks[x]<ranks[y]){
        		par[x]=y;
        		kosuu[y]=yy+xx;
        	}
         else {
        	par[y]=x;
        	if(ranks[x]==ranks[y]) ranks[x]=ranks[x]+1;
         	kosuu[x]=yy+xx;
         }
        	return;
        }
*/
int dx[4]={-1,0,0,1};
int dy[4]={0,-1,1,0};
int sumi[60][60]={0};
int a[60][60];
        signed main(){
        
        	for(int i=0;i<3;i++)for(int j=0;j<3;j++)cin>>a[i][j];
        	
        	bool bo=true;
        	
        	set<int > se;
        	for(int i=0;i<3;i++) se.insert(a[i][1]-a[i][0]);
        	if(se.size()>1) bo=false;
        	se.clear();
        	
        	for(int i=0;i<3;i++) se.insert(a[i][2]-a[i][1]);
        	if(se.size()>1) bo=false;
        	se.clear();
        	
        	for(int i=0;i<3;i++) se.insert(a[1][i]-a[0][i]);
        	if(se.size()>1) bo=false;
        	se.clear();
        	
        	for(int i=0;i<3;i++) se.insert(a[2][i]-a[1][i]);
        	if(se.size()>1) bo=false;
        	se.clear();
        	
        	if(bo) cout<<"Yes"<<endl;
        	else cout<<"No"<<endl;
        
        	return 0;
        }
        


Measured memory_bytes: 256