Seven. One to change it and the other six to sing about how good the old one was.
or
2 years old.
Cow: "Mooooove over"
Sheep: "Naaaaaaa."
or
Three. One to climb the ladder while the second kicks the ladder out from under her. And the third to say, "I knew that was too high for you dear."
or
What's the use, they'd still have bear feet
or