px,py = map(int,input().split())
qx,qy = map(int,input().split())
rx,ry = map(int,input().split())

ans = []
for x in range(-1000,1101):
    for y in range(-1000,1101):
        pd = abs(x-px) + abs(y-py)
        qd = abs(x-qx) + abs(y-qy)
        rd = abs(x-rx) + abs(y-ry)
        if pd == qd == rd:
            ans.append((x,y))

if len(ans) <= 1000:
    print(len(ans))
    if ans:
        ans.sort()
        for x,y in ans:
            print(x,y)
else:
    print(-1)