x=input()
s=0
for i in range(len(x)):
    s+=int(x[i])*2**(len(x)-1-i)
m = ""
k='123456789ABCDEF'
n=int(s)   
while n!=0:
    r = n%16
    m=k[r-1]+m
    n = n//16
print(m)