def cont(x,M):

    ret = 0
    div = M
    while x >= div:
        ret += x // div
        div *= M
    return ret

N,K,M = map(int,input().split())

q = set()
for i in range(2,10**6+1):

    if M % i == 0:
        q.add(i)
        while M % i == 0:
            M //= i
if M != 1:
    q.add(i)


ans = float("inf")
for mod in q:

    ans =  min( ans , cont(N,mod) - cont(K,mod) - cont(N-K,mod) )
print (ans)