Submission #71668658

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#define debug(arg) cout << "[" << #arg << "]: " << arg << endl
#else
#define debug(arg) 42
#endif

using llu = uint64_t;
using ll = int64_t;

#define vec vector
#define pb push_back
#define all(n) begin(n), end(n)

void solv() {
	int n, q; cin >> n >> q;
	set<pair<int, int>> fish;
	int ans = 0;
	while (q--) {
		int x, y; cin >> x >> y;
		bool good = true;
		for (int i = 0; i < 4; ++i) good &= !fish.contains({x + (i&1), y + (i >> 1)});
		if (good) {
			++ans;
			for (int i = 0; i < 4; ++i) fish.insert({x + (i&1), y + (i >> 1)});
		}
	}
	cout << ans << '\n';
}

signed main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	int t = 1;
	//cin >> t;
	while (t--) solv();
	return 0;
}

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