Виток 1, Шаг 7 - Линейный массив

Number by 3

The sequence of real numbers a1, a2,..., an is given. Find the sum and the number of positive elements which indexes are divisible by 3.


The number of elements n (n100) in a sequence is given in the first line. Next line contains n real numbers, each value does not exceed 100 by absolute value.


Print in one line the number of required elements and their sum with 2 digits after the decimal point.

Time limit 1 second
Memory limit 128 MiB
Input example #1
6 7.5 2.1 2.0 0 -3

Output example #1
1 2.10
Source SFE-2010 Variant 19