s=input()
a="0123456789ABCDEF"
result=""
for i in range(0,(4-len(s)%4)%4):
    s="0"+s
m=0
result=""
for i in range(len(s)):
    m=m*2+int(s[i])
    if i%4==3:
        result=result+a[m]
        m=0
print(result)