#include <bits/stdc++.h>  
using namespace std;  

#define int long long  

signed main() {  
    ios::sync_with_stdio(false);
    cin.tie(nullptr);  

	int H, M, A;
	cin >> H >> M >> A;

	int ans = 0;
	// for (int k = 0; k < H; k++) {
	// 	int l = ceil(1.0 * (k * M - A) / (H - 1));
	// 	int r = floor(1.0 * (k * M + A) / (H - 1));
	// 	l = max(l, 0LL), r = min(r, M - 1);		
	// 	// cerr << l << " " << r << "\n";
	// 	ans += r - l + 1;
	// }

	for (int l = 0, r; l < H; l = r + 1) {
		if ((l * M + A) / (H - 1) >= M) {
			ans += (H - l) * (M - 1);
			break;
		}
		int d = (H - 1) - (l * M + A) % (H - 1);
		int st = d / M - (d % M == 0);
		r = min(H - 1, l + st);
		ans += (r - l + 1) * ((l * M + A) / (H - 1));
	}

	for (int l = 0, r; l < H; l = r + 1) {
		if (l * M - A <= 0) {
			r = A / M;
			continue;
		}
		int d = (H - 1) - (l * M - A) % (H - 1);
		int st = d / M;
		r = min(H - 1, l + st);
		int sub = (r - l + 1) * ((l * M - A + H - 2) / (H - 1));
		ans -= sub;
	}

	ans += H;

	cout << ans << "\n";

    return 0;
}