Four young children are seated next to each other on a bench. The child on the
left cannot be older than the child on the right. The ages of 1st and 3rd children
differ by 8 years. No child is below 2 years old, neither any of them is older than
10 years old. The 2nd child is 7 years younger than the 4th child. What are the
ages of the four children?