#include <bits/stdc++.h>

using namespace std;
using ll = long long;

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

    int R, C, n;
    cin >> R >> C >> n;

    vector<int> x(n), y(n);

    for (int i = 0; i < n; ++i) {
        cin >> x[i] >> y[i];
        --x[i], --y[i];
    }

    int ans = R + C;

    for (int k = 0; k < 2; ++k) {
        for (int u = 0; u < R; ++u) {
            for (int d = 0; d + u < R; ++d) {
                vector<vector<int>> a(R);

                for (int i = 0; i < n; ++i) {
                    for (int t = d; t >= -u; --t) {
                        if (x[i] + t >= 0 && x[i] + t < R) {
                            a[x[i] + t].push_back(y[i]);
                        }
                    }
                }

                int mxx = 0, mxy = 0, mxs = 0;
                bool ok = true;

                for (int i = 0; i < R; ++i) {
                    sort(a[i].begin(), a[i].end());
                    a[i].resize(unique(a[i].begin(), a[i].end()) - a[i].begin());

                    if (a[i].empty()) {
                        ok = false;
                    } else {
                        mxx = max(mxx, a[i][0]);
                        mxy = max(mxy, C - a[i][1] - 1);
                        for (int j = 0; j + 1 < size(a[i]); ++j) {
                            mxs = max(mxs, a[i][j + 1] - a[i][j] - 1);
                        }
                    }
                }

                if (ok) {
                    ans = min(ans, max(mxx + mxy, mxs) + u + d);
                }
            }
        }

        for (int i = 0; i < n; ++i) {
            swap(x[i], y[i]);
        }
        swap(R, C);
    }

    cout << ans << '\n';

    return 0;
}