#include <iostream>
#include <stdio.h>
using namespace std;

int R, C, N;

struct p{
	int x, y;
} points[5005];

bool operator<(p &p1, p &p2){
	if(p1.x < p2.x) return 1;
	if(p1.x > p2.x) return 0;
	return p1.y < p2.y;
}

inline bool inRange(int x, int y){
	return x >= 1 && x <= R && y >= 1 && y <= C;
}

inline int mx(int x, int y){
	return x>y? x : y;
}

inline int mn(int x, int y){
	return x<y? x : y;
}

void quickSort(p s[], int l, int r)
{
    if (l < r)
    {
        int i = l, j = r;
        p x = s[l];
        while (i < j)
        {
            while(i < j && !(s[j] < x))
                j--;
            if(i < j)
                s[i++] = s[j];
            while(i < j && s[i] < x)
                i++;
            if(i < j)
                s[j--] = s[i];
        }
        s[i] = x;
        quickSort(s, l, i - 1);
        quickSort(s, i + 1, r);
    }
}

bool state[5001][5001] = {0};

int main() {
	scanf("%d%d%d", &R, &C, &N);
	for(int i = 0; i < N; i++){
		int x, y;
		scanf("%d%d", &x, &y);
		points[i].x = x;
		points[i].y = y;
		state[x][y] = 1;
	}
	quickSort(points, 0, N-1);
	int mx = 0;
	for(int i = 0; i < N-1; i++){
		int xi = points[i].x, yi = points[i].y;
		for(int j = i+1; j < N; j++){
			int xj = points[j].x, yj = points[j].y;
			int xcha = xj-xi, ycha = yj-yi;
			if(xi + mx*xcha > R){
				break;
			}
			int ttt = yi + mx*ycha;
			if(ttt > C || ttt < 1){
				continue;
			}
			if(inRange(xi-xcha, yi-ycha)) continue;
			int limit = 2147483647;
			if(xj != xi) limit = (R-xi)/xcha;
			if(yj > yi) limit = mn(limit, (C-yi)/ycha);
			else if(yj < yi) limit = mn(limit, (yi-1)/(-ycha));
			if(limit < 2) continue;
			int startx = xj, starty = yj;
			int k = 0;
			bool ky = 1;
			for(; k < limit-1; k++){
				startx += xcha, starty += ycha;
				if(!state[startx][starty]){
					ky = 0;
					break;
				}
			}
			if(ky){
				mx = limit + 1;
			}
		}
	}
	printf("%d\n", mx);
	return 0;
}