import sys x=input() y=x.replace('0x','') di={'A':10,'B':11,'C':12,'D':13,'E':14,'F':15} l=len(y) re=0 for i in range(l): if di.get(y[i]): re=re+di.get(y[i])*(16**(l-i-1)) else: re=re+int(y[i])*(16**(l-i-1)) print(re)