def main():
    l=[]
    for i in range(3):
        tmp=input()
        l.append(tmp)
    print(zen(l[0][0],l))
    
def zen(s,l):
    for i in range(3):
        for j in range(3):
            if (i+j)%2==0 and l[i][j]!=s:
                return "No"
            elif (i+j)%2!=0 and l[i][j]==s:
                return "No"
    return "Yes"
main()