#include "seats.h"
#include <algorithm>
using namespace std;
typedef long long llong;
typedef pair<int, int> pii;
int h, w, n;
vector<int> R, C;
vector<vector<int>> idx;
struct segtree {
struct node {
llong mn, ct, lz;
node() : mn(0), ct(1), lz(0) {}
node operator+(const node &p) const {
node ret;
ret.mn = min(mn, p.mn);
ret.ct = 0;
if (ret.mn == mn) ret.ct += ct;
if (ret.mn == p.mn) ret.ct += p.ct;
ret.lz = 0;
return ret;
}
} seg[1 << 21];
void spread(int i) {
seg[i << 1].mn += seg[i].lz;
seg[i << 1].lz += seg[i].lz;
seg[i << 1 | 1].mn += seg[i].lz;
seg[i << 1 | 1].lz += seg[i].lz;
seg[i].lz = 0;
}
void update(int i, int s, int e, int x, int y, llong v) {
if (e < x || y < s) return;
if (x <= s && e <= y) {
seg[i].mn += v;
seg[i].lz += v;
return;
}
spread(i);
int m = (s + e) / 2;
update(i << 1, s, m, x, y, v);
update(i << 1 | 1, m + 1, e, x, y, v);
seg[i] = seg[i << 1] + seg[i << 1 | 1];
}
int get() const {
return seg[1].ct;
}
} seg;
int getIdx(int x, int y) {
if (x < 0 || h <= x || y < 0 || w <= y) return n;
return idx[x][y];
}
void update(int x, int y, int v) {
int A[4] = { getIdx(x - 1, y - 1), getIdx(x - 1, y)
, getIdx(x, y - 1), getIdx(x, y) };
sort(A, A + 4);
seg.update(1, 0, n - 1, A[0], A[1] - 1, v);
seg.update(1, 0, n - 1, A[2], A[3] - 1, v * (1ll << 30));
}
void give_initial_chart(int H, int W, vector<int> R, vector<int> C) {
idx.resize(H, vector<int>(W, 0));
::R = R; ::C = C;
h = H; w = W; n = H * W;
for (int i = 0; i < n; ++i) {
idx[R[i]][C[i]] = i;
}
for (int i = 0; i <= h; ++i) {
for (int j = 0; j <= w; ++j) {
update(i, j, 1);
}
}
}
int swap_seats(int a, int b) {
vector<pii> ps;
for (int i = 0; i < 2; ++i) {
for (int j = 0; j < 2; ++j) {
ps.emplace_back(R[a] + i, C[a] + j);
ps.emplace_back(R[b] + i, C[b] + j);
}
}
sort(ps.begin(), ps.end());
ps.erase(unique(ps.begin(), ps.end()), ps.end());
for (pii i : ps) update(i.first, i.second, -1);
swap(idx[R[a]][C[a]], idx[R[b]][C[b]]);
swap(R[a], R[b]); swap(C[a], C[b]);
for (pii i : ps) update(i.first, i.second, 1);
return seg.get();
}
