#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1000010;
ll n,sum,cnt,flag;
int x,k;
map<ll,int>mp;
int main () {
	freopen("zhuan.in","r",stdin);
	freopen("zhuan.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	cin >> n >> x >> k;
	while (cnt<n) {
		cnt++;
		sum+=x;
		sum-=(sum/k);
		if (mp[sum]&&!flag) {
			int t=(cnt-mp[sum]);
			n-=(n/t)*t;
			flag=1;
		}
		mp[sum]=cnt;
	}
	cout << sum <<endl;
	return 0;
}