l = float(input(''))
k = str(l) + '00000000000'
index_ = k.index('.')
if int(k[index_ + 4]) >= 5:
    k = float(k[:index_ + 4]) + float('0.001')
    k = str(k)
    index_m = k.index('.')
    cha = 3 - (len(k) - index_m - 1)
    for d in range(cha):
        k += '0'
else:
    k = k[:index_ + 4]

print('{:.3f}'.format(float(k)))