#include "bits/stdc++.h"
using namespace std;
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
int R, C; cin>>R>>C;
int n; cin>>n;
vector<int> x(n), y(n);
for(int i=0;i<n;i++){
cin>>x[i]>>y[i];
}
int N = 2 * R + 1, M = 2 * C + 1;
auto check = [&](int a, int b){
vector<vector<int>> g(N + 1, vector<int>(M + 1));
vector<vector<int>> t(N + 1, vector<int>(M + 1));
for(int i=0;i<n;i++){
g[x[i]][y[i]]++;
g[x[i] + a][y[i]]--;
g[x[i]][y[i] + b]--;
g[x[i] + a][y[i] + b]++;
}
for(int i=1;i<=N;i++){
for(int j=1;j<=M;j++){
g[i][j] += g[i-1][j] + g[i][j-1] - g[i-1][j-1];
if(g[i][j]) t[i][j] = 1;
t[i][j] += t[i-1][j] + t[i][j-1] - t[i-1][j-1];
}
}
//~ cout<<a<<" "<<b<<"\n";
//~ for(int i=1;i<=N;i++){
//~ for(int j=1;j<=M;j++){
//~ cout<<(g[i][j] > 0)<<" ";
//~ } cout<<"\n";
//~ } cout<<"\n";
for(int i=R;i<=N;i++){
for(int j=C;j<=M;j++){
int cnt = t[i][j] - t[i-R][j] - t[i][j-C] + t[i-R][j-C];
if(cnt == R * C){
return true;
}
}
}
return false;
};
int res = R + C;
for(int a=1;a<=R;a++){
for(int b=1;b<=C;b++){
if(check(a, b)) res = min(res, a + b - 2);
}
}
cout<<res<<"\n";
}
