numOx = input().strip()
values = {
    'A':10,
    'B':11,
    'C':12,
    'D':13,
    'E':14,
    'F':15
}
sums = 0
j=0
for i in range(len(numOx)-1,1,-1):
    if numOx[i] in "0123456789":
        sums = int(numOx[i])*(16**j) + sums
    else:
        number = values[numOx[i]]
        sums = number*(16**j) + sums
    j += 1
print(sums)