Problems

# Squares

# Squares

Given the length of **n** segments. What is the maximum number of squares can be constructed? Each side of a square must be constructed from only one segment.

#### Input

The first line contains the number of segments **n** (**1** ≤ **n** ≤ `10`

). The second line contains ^{6}**n** integers - the length of segments with values no more than **100**.

#### Output

Print the maximum number of squares that can be constructed from the given segments.

Input example #1

9 2 2 4 2 3 2 1 2 4

Output example #1

1