#include <bits/stdc++.h>
using namespace std;

// #define int long long


int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int r,c,n;
    cin >> r >> c >> n;
    vector<pair<int,int>> points(n);
    for(auto&[a,b]:points)cin>>a>>b;
    int tar = r*c;
    auto check = [&](int chosenR,int chosenC){
        vector grid(2*r+1,vector(2*c+1,0));
        for(auto&[x,y]:points) {
            grid[x][y]++;
            grid[x+chosenR][y]--;
            grid[x][y+chosenC]--;
            grid[x+chosenR][y+chosenC]++;
        }
        for(int i=1;i<=2*r;i++) {
            for(int j=1;j<=2*c;j++) {
                grid[i][j]+=grid[i][j-1];
            }
        }
        for(int i=1;i<=2*c;i++) {
            for(int j=1;j<=2*r;j++) {
                grid[j][i]+=grid[j-1][i];
            }
        }
        for(int i=1;i<=2*r;i++) {
            for(int j=1;j<=2*c;j++) {
                grid[i][j]=min(1,grid[i][j])+grid[i-1][j]+grid[i][j-1]-grid[i-1][j-1];
            }
        }
        auto get = [&](int x1,int y1,int x2,int y2) {
            return grid[x2][y2]-grid[x1-1][y2]-grid[x2][y1-1]+grid[x1-1][y1-1];
        };
        for(int i=1;i<=chosenR;i++) {
            for(int j=1;j<=chosenC;j++) {
                if(get(i,j,i+r-1,j+c-1)==tar)return true;
            }
        }
        return false;
    };
    int ans = r+c;
    for(int R=1;R<=r;R++) {
        for(int C=1;C<=c;C++) {
            if(check(R,C)) {
                ans=min(ans,R+C-2);
            }
        }
    }
    cout << ans << '\n';
}