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Mean with While ⭐⭐

Read integers until the user enters -1. Compute and print the integer mean of all numbers read (not counting -1). You may assume there is at least one number before -1.

Input

One or more integers, one per line, ending with -1.

Output

Print the integer mean of the numbers read.

Example

Input:

5
10
15
-1

Output:

10