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#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> pii;

#define FOR(x, b, e) for(int x = (b); x <= (e); ++(x))
#define FORD(x, b, e) for(int x = (b); x >= (e); --(x))
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(a, b) for (auto&a : (b))
#define PB push_back
#define PF push_front
#define ST first
#define ND second
#define DBG(vari) cerr<<#vari<<" = "<<(vari)<<endl

template <typename T>
std::ostream& operator<<(std::ostream &output, const vector<T> &vec)
{
    output << "[";
    FOREACH(x, vec) output << x << ", ";
    output << "]";
    return output;
}

template <typename T, typename U>
std::ostream& operator<<(std::ostream &output, const pair<T,U> &p)
{
    output << "(";
    output << p.ST << ", " << p.ND;
    output << ")";
    return output;
}

vector<set<int>> P;

inline bool jest(int x, int y) {
  return P[x].find(y) != P[x].end();
}

inline bool pusty(int x, int y, vector<set<int>>& visited) {
  return (P[x].find(y) == P[x].end() || visited[x].find(y) != visited[x].end());
}

inline bool usuwalny(int x, int y, vector<set<int>>& visited) {
  return (pusty(x-1,y,visited) && pusty(x+1,y,visited)) || (pusty(x,y-1,visited) && pusty(x,y+1,visited));
}

void solve(int n) {
  queue<pii> q;
  vector<set<int>> visited(n+2);
  int ctr=0;

  FOR(x, 1, n) {
    FOREACH(y, P[x]) {
      if (usuwalny(x,y,visited)) {
        visited[x].insert(y);
        q.emplace(x,y);
        ctr++;
      }
    }
  }

  while (SIZE(q)>0) {
    auto u = q.front(); q.pop();
    int x, y; tie(x,y) = u;

    vector<pii> sasiedzi({{x - 1, y}, {x + 1, y}, {x, y - 1}, {x, y + 1}}); 

    FOREACH(s, sasiedzi) {
      int xx, yy; tie(xx,yy) = s;
      if (!jest(xx,yy)) continue;

      if (visited[xx].find(yy) == visited[xx].end()) {
        if (usuwalny(xx,yy,visited)) {
          visited[xx].insert(yy);
          q.emplace(xx,yy);
          ctr++;
        }
      }
    }
  }

  cout << ctr << endl;
}

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

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

  P.resize(n+2);

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

  solve(n);

  REP(i, q) {
    int x, y; cin >> x >> y; 
    if (!jest(x,y))
      P[x].insert(y);
    else
      P[x].erase(P[x].find(y));
    solve(n);
  }
}