[백준] 설탕배달 2839 solved by Python

N = int(input())

five_kg_bag = 0
three_kg_bag = 0
while N >= 0:
    if N % 5 == 0:
        five_kg_bag += N // 5
        print(five_kg_bag + three_kg_bag)
        break
    else:
        N -= 3
        three_kg_bag += 1
else:
    print(-1)