package main

import (
	"os"
	"fmt"
)

func accountBalanceAfterPurchase(purchaseAmount int) int {
	var firstDigit int = purchaseAmount % 10
	if firstDigit >= 5 {
		return 100 - (purchaseAmount + (10 - firstDigit))
	}

	return 100 - (purchaseAmount - firstDigit)
}

func main() {
	r := func(purchaseAmount int, exp int) {
		fmt.Printf(
			"accountBalanceAfterPurchase(%v) = %v | exp: %v\n",
			purchaseAmount,
			accountBalanceAfterPurchase(purchaseAmount),
			exp,
		)
	}

	r(9, 90)
	r(15, 80)
	r(10, 90)

	os.Exit(0)
}