Problem:
Score : 100 points

Problem Statement

Joisino wants to evaluate the formula "A op B".
Here, A and B are integers, and the binary operator op is either + or -.
Your task is to evaluate the formula instead of her.

Constraints

1≦A,B≦10^9

op is either + or -.

Input

The input is given from Standard Input in the following format:

A op B

Output

Evaluate the formula and print the result.

Sample Input 1

1 + 2

Sample Output 1

3

Since 1 + 2 = 3, the output should be 3.

Sample Input 2

5 - 7

Sample Output 2

-2

Solution in Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.util.*

val mod: Long = (Math.pow(10.0, 9.0) + 7).toLong()

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val n = sc.nextInt()
//    val aList = mutableListOf<Int>()
//    for (i in 0 until n) {
//        aList.add(sc.nextInt())
//    }
//
//    var bList = mutableListOf<Int>()
//    for (i in 1..n / 2) {
//        bList.add(n - i * 2 + 1)
//    }
//    bList = (bList + bList.reversed()).toMutableList()
//    if (n % 2 != 0) bList.add(bList.size / 2, 0)
//
//    val answerList = mutableListOf<Int>()
//    val aList2 = aList.toMutableList()
//    bList.forEach {
//        val indexOf = aList2.indexOf(it)
//        if (indexOf != -1) {
//            answerList.add(aList2[indexOf])
//            aList2.removeAt(aList2.indexOf(it))
//        }
//    }
//    if (bList != answerList) {
//        println(0)
//        return
//    }

    val ans = Math.pow(2.0, (n / 2).toDouble()) % mod
    println(ans.toLong())
}