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#include <bits/stdc++.h>

using namespace std;

struct Block
{
    int x, y;
};

struct Node
{
    int left, right, up, down;
};

const int MAX_BLOCKS = 75002 * 2;
const int MAX_WIDTH_HEIGHT = 200002;

int height, width;
Block blocks[MAX_BLOCKS];
int blocks_cnt;
unordered_map<int, int> block_idx_by_yx[MAX_WIDTH_HEIGHT];

Node graph[MAX_BLOCKS];
bool removed[MAX_BLOCKS];
unordered_set<int> starting_blocks;
bool idx_discarded[MAX_BLOCKS];
vector<int> discarded_idxs;

bool can_remove(int idx)
{
    int left = removed[graph[idx].left] ? -1 : graph[idx].left;
    int right = removed[graph[idx].right] ? -1 : graph[idx].right;
    int up = removed[graph[idx].up] ? -1 : graph[idx].up;
    int down = removed[graph[idx].down] ? -1 : graph[idx].down;
    
    return (left == -1 && right == -1) || (up == -1 && down == -1);
}

int que[MAX_BLOCKS];
int que_size;

int bfs(int idx)
{
    int curr_idx, neighbor_idx, i;
    int neighbors[4];
    int removed_cnt = 0;
    
    que_size = 0;
    que[que_size++] = idx;
    while (que_size > 0)
    {
        curr_idx = que[--que_size];
        if (removed[curr_idx])
        {
            continue;
        }
        
        removed[curr_idx] = true;
        ++removed_cnt;
        
        neighbors[0] = graph[curr_idx].left;
        neighbors[1] = graph[curr_idx].right,
        neighbors[2] = graph[curr_idx].up;
        neighbors[3] = graph[curr_idx].down;
        
        for (i = 0; i < 4; ++i)
        {
            neighbor_idx = neighbors[i];
            if (neighbor_idx == -1 || removed[neighbor_idx])
            {
                continue;
            }
            
            if (can_remove(neighbor_idx))
            {
                que[que_size++] = neighbor_idx;
            }
        }
    }
    
    return removed_cnt;
}

int calc()
{
    int removed_cnt = 0;
    
    for (int starting_block : starting_blocks)
    {
        removed_cnt += bfs(starting_block);
    }
    return removed_cnt;
}

void update_block(int i)
{
    int y = blocks[i].y;
    int x = blocks[i].x;
    
    graph[i].left = block_idx_by_yx[y].count(x - 1) ? block_idx_by_yx[y][x - 1] : -1;
    graph[i].right = block_idx_by_yx[y].count(x + 1) ? block_idx_by_yx[y][x + 1] : -1;
    graph[i].up = block_idx_by_yx[y - 1].count(x) ? block_idx_by_yx[y - 1][x] : -1;
    graph[i].down = block_idx_by_yx[y + 1].count(x) ? block_idx_by_yx[y + 1][x] : -1;
    
    if (can_remove(i) && !idx_discarded[i])
    {
        starting_blocks.insert(i);
    }
    else
    {
        starting_blocks.erase(i);
    }
}

void update_blocks()
{
    starting_blocks.clear();
    for (int i = 0; i < blocks_cnt; ++i)
    {
        if (idx_discarded[i])
            continue;
        
        update_block(i);
    }
}

void update_starting_block(int y, int x)
{
    if (!block_idx_by_yx[y].count(x))
    {
        return;
    }
    int idx = block_idx_by_yx[y][x];
    update_block(idx);
}

void process_query(int y, int x)
{
    int idx;
    if (!block_idx_by_yx[y].count(x))
    {
        if (!discarded_idxs.empty())
        {
            idx = discarded_idxs.back();
            discarded_idxs.pop_back();
            idx_discarded[idx] = false;
        }
        else
        {
            idx = blocks_cnt++;
        }
        
        blocks[idx].x = x;
        blocks[idx].y = y;
        block_idx_by_yx[y][x] = idx;
    }
    else
    {
        idx = block_idx_by_yx[y][x];
        discarded_idxs.push_back(idx);
        
        idx_discarded[idx] = true;
        block_idx_by_yx[y].erase(x);
    }
    
    update_block(idx);
    update_starting_block(y, x - 1);
    update_starting_block(y, x + 1);
    update_starting_block(y - 1, x);
    update_starting_block(y + 1, x);
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int queries_cnt;
    int x, y;
    int i;
    
    cin >> height >> width >> blocks_cnt >> queries_cnt;
    for (i = 0; i < blocks_cnt; ++i)
    {
        cin >> blocks[i].y >> blocks[i].x;
        block_idx_by_yx[blocks[i].y][blocks[i].x] = i;
    }
    
    for (i = 0; i < blocks_cnt; ++i)
    {
        update_block(i);
    }
    
    int res = calc();
    cout << res << "\n";
    while (queries_cnt--)
    {
        memset(removed, 0, blocks_cnt);
        
        cin >> y >> x;
        process_query(y, x);
        
        res = calc();
        cout << res << "\n";
    }

    return 0;
}