Untitled

#include <bits/stdc++.h>

using namespace std;
using ull = uint64_t;
using ll = int64_t;
using ui = uint32_t;
using pii = pair<int, int>;

#define fi first
#define se second
#define mp make_pair
#define all(x) (x).begin(),(x).end()

const int INF = 1e9;

vector<pii> moves = {
        mp(2, 1), mp(2, -1), mp(1, 2), mp(1, -2),
        mp(-1, 2), mp(-1, -2), mp(-2, 1), mp(-2, -1)
};

int main() {

    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);

    int n, m, s, t, queries;
    cin >> n >> m >> s >> t >> queries;

    s--, t--;
    queue<pii> q;
    vector<vector<int>> dist(n, vector<int>(m, INF));
    dist[s][t] = 0, q.push(mp(s, t));

    auto isValid = [&](int x, int y) {
        return (x >= 0 && x < n && y >= 0 && y < m);
    };

    while (!q.empty()) {
        auto [x, y] = q.front(); q.pop();
        for (pii& mv: moves) {
            int dx = x + mv.fi;
            int dy = y + mv.se;
            if (isValid(dx, dy) && dist[dx][dy] == INF) {
                q.push(mp(dx, dy));
                dist[dx][dy] = dist[x][y] + 1;
            }
        }
    }

    ll ans = 0;
    for (int i = 0; i < queries; ++i) {
        int x, y;
        cin >> x >> y;
        x--, y--;
        if (dist[x][y] == INF) {
            cout << -1;
            return 0;
        }
        ans += dist[x][y];
    }

    cout << ans;

    return 0;
}