/**
_ _ __ _ _ _ _ _ _
|a ||t ||o d | |o |
| __ _| | _ | __| _ |
| __ |/_ | __ /__\ / _\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 300;
const ll INF = LLONG_MAX;
int H, W;
int N;
int X[N_MAX + 2], Y[N_MAX + 2];
int xs[N_MAX + 2], cntx;
int ys[N_MAX + 2], cnty;
int order[N_MAX + 2];
multiset <int> S;
multiset <int> diffs;
void add_S (int y) {
multiset <int> :: iterator it = S.insert(y);
if (it != S.begin()) {
if (*next(it) > 1) {
diffs.erase(diffs.find(*next(it) - *prev(it)));
if (*it > 1) {
diffs.insert(*it - *prev(it));
}
}
}
if (*next(it) > 1) {
diffs.insert(*next(it) - *it);
}
}
void del_S (int y) {
multiset <int> :: iterator it = S.find(y);
if (it != S.begin()) {
if (*next(it) > 1) {
if (*it > 1) {
diffs.erase(diffs.find(*it - *prev(it)));
}
diffs.insert(*next(it) - *prev(it));
}
}
if (*next(it) > 1) {
diffs.erase(diffs.find(*next(it) - *it));
}
S.erase(it);
}
ll solve (int h) {
S.clear(); S.insert(W + 1);
diffs.clear();
// cout << "solve(h=" << h << "):\n";
int w = 0;
for (int k = 2, i = 1, j = 1; k <= cntx + 1; k++) {
if (xs[k] - 1 <= 0) {
continue;
}
// cout << xs[k] - 1 << ":\n";
while (i <= N && X[order[i]] <= xs[k] - 1) {
// cout << "insert " << Y[order[i]] << "\n";
add_S(Y[order[i++]]);
}
while (j < i && X[order[j]] + h < xs[k] - 1) {
// cout << "delete " << Y[order[j]] << "\n";
del_S(Y[order[j++]]);
}
// for (int d : diffs) {
// cout << d << " ";
// }
// cout << "\n";
if (S.empty() == true || *S.begin() > 1) {
return INF;
}
w = max(w, *diffs.rbegin() - 1);
}
// cout << " => " << h << " + " << w << "\n";
return (ll) h + w;
}
//bool brute (int U, int D, int L, int R) {
// for (int x = 1; x <= H; x++) {
// for (int y = 1; y <= W; y++) {
// bool ok = false;
// for (int i = 1; i <= N; i++) {
// if (X[i] - U <= x && x <= X[i] + D && Y[i] - L <= y && y <= Y[i] + R) {
// ok = true;
// break;
// }
// }
// if (ok == false) {
// return false;
// }
// }
// }
// return true;
//}
signed main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
// mt19937 rnd(time(0));
cin >> H >> W;
cin >> N;
// H = W = 40; N = 10;
for (int i = 1; i <= N; i++) {
cin >> X[i] >> Y[i];
// X[i] = rnd() % H + 1;
// Y[i] = rnd() % W + 1;
// cout << X[i] << " " << Y[i] << "\n";
xs[i] = X[i]; ys[i] = Y[i];
}
sort(xs + 1, xs + N + 1);
sort(ys + 1, ys + N + 1);
cntx = (unique(xs + 1, xs + N + 1) - (xs + 1));
cnty = (unique(ys + 1, ys + N + 1) - (ys + 1));
xs[cntx + 1] = H + 1; ys[cnty + 1] = W + 1;
iota(order + 1, order + N + 1, 1);
sort(order + 1, order + N + 1, [&] (const int &i, const int &j) {
return X[i] < X[j];
});
ll answer = INF;
for (int kx = 1; kx <= cntx; kx++) {
for (int ky = 1; ky <= cnty; ky++) {
int dx = xs[kx] - 1, dy = ys[ky] - 1;
for (int i = 1; i <= N; i++) {
X[i] -= dx; Y[i] -= dy;
}
for (int i = 1; i <= cntx; i++) {
xs[i] -= dx;
}
// cout << "delta=(" << dx << "," << dy << ")\n";
for (int i = 1; i <= cntx; i++) {
for (int j = i + 1; j <= cntx + 1; j++) {
if ((ll) (xs[j] - xs[i] - 1) + dy <= answer) {
answer = min(answer, solve(xs[j] - xs[i] - 1));
}
}
}
// cout << "\n\n\n";
for (int i = 1; i <= N; i++) {
X[i] += dx; Y[i] += dy;
}
for (int i = 1; i <= cntx; i++) {
xs[i] += dx;
}
}
}
cout << answer << "\n";
// for (int U = 0; U < H; U++) {
// for (int D = 0; D < H; D++) {
// for (int L = 0; L < W; L++) {
// for (int R = 0; R < W; R++) {
// if (U + D + L + R < answer && brute(U, D, L, R) == true) {
// cout << U << " " << D << " " << L << " " << R << "\n";
// for (int i = 1; i <= N; i++) {
// cout << X[i] - U << " " << Y[i] - L << " ";
// cout << X[i] - U << " " << Y[i] + R << "\n";
// cout << X[i] - U << " " << Y[i] - L << " ";
// cout << X[i] + D << " " << Y[i] - L << "\n";
// cout << X[i] + D << " " << Y[i] + R << " ";
// cout << X[i] + D << " " << Y[i] - L << "\n";
// cout << X[i] + D << " " << Y[i] + R << " ";
// cout << X[i] - U << " " << Y[i] + R << "\n";
// }
// return 0;
// }
// }
// }
// }
// }
return 0;
}
