#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
int main() {
    ll N,K,M,an=0;
    cin>>N>>K>>M;
    ll A=N-K;
    map<ll,ll> P;
    for(ll i=2;i*i<=M;i++){
        if(M%i==0){
            while(M%i==0){
                P[i]++;
                M/=i;
            }
        }
    }
    if(M!=1)P[M]++;
    ll AN=1e18;
    for(auto p:P){
        ll T=N;
        ll Y=K;
        ll U=A;
        ll m=p.first;
        rep(i,70){
            an+=(T/=m)-(Y/=m)-(U/=M);
        }
        AN=min(AN,an/p.second);
        an=0;
    }
    cout<<AN<<endl;
    
}