407062: GYM102697 033 Free Throws

While watching a basketball game, you wonder what your team's total free throw percentage is. You are given how many free throws each player on your team has made and attempted. Given these values, calculate your team's free throw percentage.

The first line of input consists of a positive integer $$$n$$$: the number of players on your team. The next $$$n$$$ lines consist of two space-separated integers: how many free throws each player has made and attempted, respectively.

Output a single decimal number, representing your team's free throw percentage during the game. Round your answer to two decimal places.

4
1 5
3 4
7 7
6 8

70.83