백준 2839 설탕 배달 swift

import Foundation

 

 

var n = Int(readLine() ?? "") ?? 0

var count = 0

while true {

    if n % 5 == 0 {

        count = count + n/5

        break

    }

    n = n - 3

    count = count + 1

    

    if n < 0 {

        count = -1

        break

    }

}

print(count)