s = input('') dic = {'0':0,'1':1,'2':2,'3':3,'4':4,'5':5,'6':6,'7':7,'8':8,'9':9,'A':10,'B':11,'C':12,'D':13,'E':14,'F':15} L = len(s) X = 1 s10=0 for i in range(L): if i >= L-2: break str2num = dic[s[L-1-i]] s10 += str2num * X X *= 16 print(s10)