import sys
input=sys.stdin.readline
##n,m=map(int,input().split())
##a=[list(map(int,input().split())) for _ in range(n)]
n,k=map(str,input().split())
int(k)
ans=0
ii=0
for i in range(len(n)-1,-1,-1):
  if '9'>=n[i]>='0':
    ans+=(int(k)**ii)*int(n[i])
  else:
    ans+=(int(k)**ii)*(int(ord(n[i])-ord('A'))+10)
  ii+=1
print(ans)