Classify the Access a[-1]

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

An array $a$ contains exactly $n$ elements indexed from $0$ through $n-1$. Consider the expression a[-1].

A negative index is outside the array's valid index range. Classify this access under the C array rules. Do not predict any value from memory before the array.

Input

One line contains the integer $n$.

Output

Print exactly UNDEFINED_BEHAVIOR.

Subtasks

Subtask 1 (100 points): $1\le n\le10^9$.

Examples

Input

8

Output

UNDEFINED_BEHAVIOR

Explanation

For $n=8$, valid indices are $0$ through $7$. Index $-1$ is below the lower bound $0$, so a[-1] is outside the array. Reading through this access has no defined result in C and a program must not rely on an accidental memory value.