Synthax error - (if function) basic learning

I'm learning python from the very beginning as I'm a layman in this regard. While watching a course I'm following the instructor's footsteps, writing the same lines, but I got an unexpected Synthax error, in a basic if command.

Could you tell me what my error is here? I tried to write the code again, on other platforms, but I don't know what happened in this case.

x = 3
y = 1000000000

if x > y
  print ("yes")

if y > x 
  print ("no")

File "<ipython-input-40-f64d6f2a15e2>", line 4
    if x > y
            ^
SyntaxError: invalid syntax