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#include <bits/stdc++.h>
using namespace std;

int N, M, K, Q;

struct block {
	int right, left, up, down;
	bool active;
	bool taken_off;
};

vector<block> blocks; // not all blocks have to be active in this list
map<pair<int, int>, int> MAP; // all blocks in this map are active.

void add_block(int x, int y){
	int i = blocks.size();
	int j;
	block new_block;
	new_block.active = true;

	if(MAP.find(make_pair(x - 1, y)) != MAP.end()){
		j = MAP[make_pair(x - 1, y)];
		new_block.left = j;
		blocks[j].right = i;
	} else {
		new_block.left = -1;
	}

	if(MAP.find(make_pair(x + 1, y)) != MAP.end()){
		j = MAP[make_pair(x + 1, y)];
		new_block.right = j;
		blocks[j].left = i;
	} else {
		new_block.right = -1;
	}

	if(MAP.find(make_pair(x, y + 1)) != MAP.end()){
		j = MAP[make_pair(x, y + 1)];
		new_block.up = j;
		blocks[j].down = i;
	} else {
		new_block.up = -1;
	}

	if(MAP.find(make_pair(x, y - 1)) != MAP.end()){
		j = MAP[make_pair(x, y - 1)];
		new_block.down = j;
		blocks[j].up = i;
	} else {
		new_block.down = -1;
	}

	MAP[make_pair(x, y)] = i;
	blocks.push_back(new_block);
}

void remove_block(int x, int y, int i){
	int j;

	j = blocks[i].left; 
	if(j >= 0){
		blocks[j].right = -1;
	}

	j = blocks[i].right; 
	if(j >= 0){
		blocks[j].left = -1;
	}

	j = blocks[i].up; 
	if(j >= 0){
		blocks[j].down = -1;
	}

	j = blocks[i].down; 
	if(j >= 0){
		blocks[j].up = -1;
	}

	blocks[i].active = false;
	MAP.erase(make_pair(x, y));
}

void process(){
	int ans = 0;
	queue<int> BFS;

	for(int i = 0; i < blocks.size(); i++){
		if(!blocks[i].active) continue;

		blocks[i].taken_off = false;
		BFS.push(i);
	}

	bool up, down, left, right;
	while(!BFS.empty()){
		int x = BFS.front();
		BFS.pop();

		if(blocks[x].taken_off) continue;

		left = blocks[x].left == -1 || blocks[blocks[x].left].taken_off;
		right = blocks[x].right == -1 || blocks[blocks[x].right].taken_off;
		up = blocks[x].up == -1 || blocks[blocks[x].up].taken_off;
		down = blocks[x].down == -1 || blocks[blocks[x].down].taken_off;

		if((left && right) || (up && down)){
			blocks[x].taken_off = true;
			ans++;

			if(blocks[x].left >= 0){
				BFS.push(blocks[x].left);
			}
			if(blocks[x].right >= 0){
				BFS.push(blocks[x].right);
			}
			if(blocks[x].up >= 0){
				BFS.push(blocks[x].up);
			}
			if(blocks[x].down >= 0){
				BFS.push(blocks[x].down);
			}
		}
	}

	cout << ans << '\n';
}

int main(){
	cin.tie(NULL);
	ios_base::sync_with_stdio(0);

	cin >> N >> M >> K >> Q;

	for(int i = 0; i < K; i++){
		int x, y;
		cin >> x >> y;

		add_block(x, y);
	}

	process();

	for(int i = 0; i < Q; i++){
		int x, y;
		cin >> x >> y;

		if(MAP.find(make_pair(x, y)) == MAP.end()){
			add_block(x, y);
		} else {
			remove_block(x, y, MAP[make_pair(x, y)]);
		}

		process();
	}
}