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#include <bits/stdc++.h>

using namespace std;
using LL = long long;
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define REP(i, n) FOR(i, 0, (n) - 1)
#define ssize(x) int(x.size())

template<class A, class B> auto &operator<<(ostream &o, pair<A, B> p) {
    return o << '(' << p.first << ", " << p.second << ')';
}

template<class T> auto operator<<(ostream &o, T x) -> decltype(x.end(), o) {
    o << '{'; int i = 0; for (auto e : x) o << (", ")+2*!i++ << e;
    return o << '}';
}

#ifdef DEBUG
#define debug(x...) cerr << "[" #x "]: ", [](auto... $) {((cerr << $ << "; "), ...); }(x), cerr << '\n';
#else
#define debug(...) {}
#endif


vector<int> dx = {0, 1, 0, -1};
vector<int> dy = {-1, 0, 1, 0};

set<pair<int, int>> present;
set<pair<int, int>> moovable;
vector<pair<int, int>> todo;


bool is_moovable(int x, int y) {
    if (present.find({x, y}) == present.end())
        return false;
    if (moovable.find({x, y}) != moovable.end())
        return false;

    bool hor = (present.find({x - 1, y}) == present.end() &&
            present.find({x + 1, y}) == present.end());
    bool ver = (present.find({x, y - 1}) == present.end() &&
            present.find({x, y + 1}) == present.end());
    return hor || ver;
}


void solve() {
    vector<pair<int, int>> removed;

    for (auto [x, y] : moovable) {
        removed.emplace_back(x, y);
        present.erase({x, y});
        REP(i, 4) {
            int xx = x + dx[i], yy = y + dy[i];
            if (is_moovable(xx, yy))
                todo.emplace_back(xx, yy);
        }
    }

    while (!todo.empty()) {
        auto [x, y] = todo.back();
        todo.pop_back();
        auto iter = present.find({x, y});
        if (iter == present.end())
            continue;

        removed.emplace_back(x, y);
        present.erase(iter);
        REP(i, 4) {
            int xx = x + dx[i], yy = y + dy[i];
            if (is_moovable(xx, yy))
                todo.emplace_back(xx, yy);
        }
    }

    cout << ssize(removed) << '\n';
    for (auto [x, y] : removed)
        present.insert({x, y});
}


int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m, k, q;
    cin >> n >> m >> k >> q;

    REP(i, k) {
        int x, y;
        cin >> x >> y;
        present.insert({x, y});
    }

    for (auto [x, y] : present) {
        if (is_moovable(x, y))
            moovable.insert({x, y});
    }

    solve();
    while (q--) {
        int x, y, xx, yy;
        cin >> x >> y;

        auto iter = present.find({x, y});
        if (iter == present.end()) {
            present.insert({x, y});
            if (is_moovable(x, y))
                moovable.insert({x, y});
            
            REP(i, 4) {
                xx = x + dx[i], yy = y + dy[i];
                auto iterr = moovable.find({xx, yy});
                if (iterr != moovable.end()) {
                    moovable.erase(iterr);
                    if (is_moovable(xx, yy))
                        moovable.insert({xx, yy});
                }
            }
        }
        else {
            present.erase({x, y});
            auto iterr = moovable.find({x, y});
            if (iterr != moovable.end())
                moovable.erase({x, y});

            REP(i, 4) {
                xx = x + dx[i], yy = y + dy[i];
                if (is_moovable(xx, yy))
                    moovable.insert({xx, yy});
            }
        }

        solve();
    }

    return 0;
}