import math
num = int(input("Enter a Binary Number: "));
copyNum = num
arr = [0]*50
i = -1
total = 0
while(copyNum != 0):
i += 1
arr[i] = copyNum % 10
copyNum = math.floor(copyNum / 10)
for j in range(i, -1, -1):
total += arr[j] * math.pow(2, j)
print("Decimal number of %d (binary) is %d" % (num, math.floor(total)))