#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
// using namespace atcoder;
// using mint = modint1000000007;
// const int mod = 1000000007;
// using mint = modint998244353;
// const int mod = 998244353;
// const int INF = 1e9;
// const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, l, r) for (int i = (l); i < (r); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, l, r) for (int i = (r)-1; i >= (l); --i)
#define all(x) (x).begin(), (x).end()
#define allR(x) (x).rbegin(), (x).rend()
#define P pair<int, int>
template<typename A, typename B> inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; }

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	int n, m, k; cin >> n >> m >> k;
	vector<int>v0, v1;
	rep(i, k)v0.push_back(i);
	rep2(i, k, n - 1)v1.push_back(i);
	v0.push_back(n - 1);

	int full = n * (n - 1) / 2;
	int can = v0.size() - 1 + 2 * v1.size() + v1.size() * (v1.size() + 1) / 2;
	if (can < full - m) {
		cout << "No" << endl;
		return 0;
	}
	return -1;
	return 0;
}