First Zero Position

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Find the first 1-based position whose value equals zero among $n$ integers. Print -1 if absent or $n=0$. Here zero is a searchable data value, not an input terminator.

Input

First $n$, then exactly $n$ integers $a_i\in[-10^6,10^6]$, separated by whitespace.

Output

Print the position of the first zero, or -1.

Subtasks

• Subtask 1 (20%): $0\le n\le 8$; $-10^6\le a_i\le10^6$.

• Subtask 2 (30%): $0\le n\le 1000$; $-10^6\le a_i\le10^6$.

• Subtask 3 (50%): $0\le n\le 100000$; $-10^6\le a_i\le10^6$.

Examples

Example 1

Input:

5
2 0 0 4 0

Output:

2

Explanation:

Report the first zero, not later occurrences.

Example 2

Input:

0

Output:

-1

Explanation:

Report the first zero, not later occurrences.