N = int(input())
if N < 100:
    v = 0
    for i in range(1000):
        if i % 5 <= 2:
            v += 1
        else:
            v -= 1
        if v == N:
            print(i + 1)
            exit()
else:
    ans = (N - 100) * 5
    N = 100
    v = 0
    for i in range(1000):
        if i % 5 <= 2:
            v += 1
        else:
            v -= 1
        if v == N:
            print(ans + i + 1)
            exit()