s = input()
s = list(s)
sl = s[2:]
list1 = ['A','B','C','D','E','F','0','1','2','3','4','5','6','7','8','9']
list2 = [10, 11, 12, 13, 14,15,0,1,2,3,4,5,6,7,8,9]
d = dict(zip(list1,list2))  
len_1 = len(sl)
totoal_value = 0
for i in range(len(sl)):
    totoal_value += d[sl[i]]*(16**(len_1-1-i))
print(totoal_value)