#include <bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;
using ll = long long;
const int N = 2000010, MOD = 1e9 + 7, INF = 0x3f3f3f3f;
int n, m, w[N];

ll qmi(ll a, ll b, ll c) { ll res = 1; while (b) { if (b & 1) res = res * a % c; a = a * a % c; b >>= 1; } return res; }

void solve() {
	scanf("%d%d", &n, &m);
	if ((m & 1) || (n & 1)) {
		ll t;
		if (n & 1) t = (n - 1) / 2 % m;
		else t = m > 1 ? (n - 1) * (m + 1ll) / 2 % m : 0;
		printf("%lld\n", t);
	} else puts("NaN");
}

int main() {
	int T = 1;
	// scanf("%d", &T);
	while (T--) solve();
	return 0;
}