#include //#include 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 endl "\n" #define P pair template inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); long long n, m; cin >> n >> m; setsx, sy; rep(i, m) { long long x, y; cin >> x >> y; x--, y--; sx.insert(x + y); sy.insert(x - y); } long long ans = 0; vector>syv(2); for (auto e : sy) { syv[abs(e) % 2].push_back(e); } for (auto e : sx) { long long mnx, mny, mxx, mxy; if (e < n) { mnx = e; mny = 0; mxx = 0; mxy = e; } else { mnx = n - 1; mny = e - (n - 1); mxx = e - (n - 1); mxy = n - 1; } ans += mxy - mny + 1; ans -= ( upper_bound(all(syv[abs(mnx - mny) % 2]), mnx - mny) - lower_bound(all(syv[abs(mnx - mny) % 2]), mxx - mxy) ); } for (auto e : sy) { long long mn, mx; if (e <= 0) { mn = -e; mx = n - 1; } else { mn = 0; mx = (n - 1) - e; } ans += mx - mn + 1; } cout << ans << endl; return 0; }