Sum Until Zero

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Read a sequence of integers ending at its first zero. Sum all preceding, nonzero values, which can be positive or negative. Do not include the terminating zero. If zero comes first, the sum is zero.

Input

Integers separated by whitespace; the first zero terminates the sequence.

Output

Print one integer: the sum before the first zero.

Subtasks

• Subtask 1 (20%): At most 5 preceding values, abs(ai) <= 10.
• Subtask 2 (30%): At most 200 preceding values, abs(ai) <= 10^4.
• Subtask 3 (50%): At most 10^5 preceding values, abs(ai) <= 10^6.

Examples

Example 1

Input

3 -1 0

Output

2

Explanation

The running sum changes 0 -> 3 -> 2; zero terminates input.

Example 2

Input

0

Output

0

Explanation

There are no values before zero, so the empty sum is zero.