n = int(input());
b = int(input());
def AnyToDec(n,b):
# Write your code here
p=1
res = 0
while(n>0):
rem = n%10
n = int(n/10)
res = res + p*rem
p = p * b
return res
if __name__ == "__main__":
res = AnyToDec(n,b)
print(res)