include <bits/stdc++.h>

using namespace std; int main() {

long long n, m, k, h, z;
cin >> n >> m >> k;
if (m / (k - 1) >= n) {
	h = n - 1;
	z = (m - h * (k - 1)) % k;
} else {
	h = m / (k - 1);
	z = m % (k - 1);
}
long long v = h * (k - 1) + z;
cout << v;
return 0;

}