n1 = list(input())
i = len(n1) - 1
n2 = 0
while i != -1:
    n2 += int(n1[i]) * 2 ** (len(n1) - 1 - i)
    i -= 1

rlist = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F']
ans = []
k = n2 // 16
r = n2 % 16
ans.append(rlist[r])
while k != 0:
    r = k % 16
    k = k // 16
    ans.append(rlist[r])
ans.reverse()
print(''.join(ans))