from functools import lru_cache
H, A = map(int, input().split())
from math import ceil, floor

import sys
sys.setrecursionlimit(10**7)

@lru_cache
def dfs(num):
    if num == 0:
        return 0
    elif num == 1:
        return 1
    else:
        return dfs(num//A)*2+1
    
print(dfs(H))