n=input()
while len(n)%4!=0:
    n="0"+n
a=0
x=0
p=""
for i in n:
    a=2*a+int(i)
    x+=1
    if x%4==0:
        if a>9:
            p+=chr(ord("A")+a-10)
        else:
            p+=str(a)
        a=0
print(p)