백준 14916. 거스름돈

https://www.acmicpc.net/problem/14916

복잡한 더티코드...

n = int(input())
ans, k, flag = 0,0,0

if (n%5) % 2 == 0:
    ans += n//5 + ((n%5) // 2)
    flag = 1
else:
    while (n//5)-k >= 0:
        if (n - 5*((n//5)-k)) % 2 == 0:
            ans += (n//5)-k + ((n - 5*((n//5)-k)) // 2)
            flag = 1
            break
        k += 1

if flag == 1:
    print(ans)
else:
    print(-1)

깔끔한 코드

n = int(input())
ans = 0

while n > 0:
    if n % 5 == 0:
        ans += n // 5
        break
    n -= 2
    ans += 1

if n < 0:
    print(-1)
else:
    print(ans)