#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

//#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; }

bool f[100010], f2[100010], tmp[100010];

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n, m, k; cin >> n >> m >> k;
	using P = pair<int, int>;
	map<P, int> mp;
	vector<int> x(k), y(k); rep(i, 0, k) {
		cin >> x[i] >> y[i];
		mp[P(x[i], y[i])] = i;
	}
	auto inrange = [&](int i, int j) { return i >= 0 && i < n && j >= 0 && j < m; };
	int ans = 2;

	//????????????
	queue<int> q, q2;
	rep(i, 0, k) {
		if (x[i] == 0 || y[i] == m - 1) {
			q.emplace(i);
		}
	}

	memset(f, 0, sizeof(f));
	memset(tmp, 0, sizeof(tmp));
	while (q.size()) {
		int idx = q.front(); q.pop();
		if (f[idx])continue;
		f[idx] = true;
		rep(dx, -1, 2)rep(dy, -1, 2) {
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (!mp.count(P(nx, ny)))continue;
			int nidx = mp[P(nx, ny)];
			if (f[nidx])continue;
			q.emplace(nidx);
		}
		rep(dx, -2, 3)rep(dy, -2, 3) {
			if (max(abs(dx), abs(dy)) <= 1)continue;
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (mp.find(P(nx, ny)) == mp.end())continue;
			int nidx = mp[P(nx, ny)];
			if (f[nidx])continue;
			if (tmp[nidx])continue;
			tmp[nidx] = true;
			q2.emplace(nidx);
		}
	}
	memset(f2, 0, sizeof(f2));
	while (q2.size()) {
		int idx = q2.front(); q2.pop();
		if (f2[idx])continue;
		f2[idx] = true;
		rep(dx, -1, 2)rep(dy, -1, 2) {
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (mp.find(P(nx, ny)) == mp.end())continue;
			int nidx = mp[P(nx, ny)];
			if (f2[nidx])continue;
			q2.emplace(nidx);
		}
	}

	rep(i, 0, k) {
		if (x[i] == n - 1 || y[i] == 0) {
			if (f[i]) {
				chmin(ans, 0);
			}
		}
	}
	rep(i, 0, k) {
		if (x[i] == n - 2 || y[i] == 1) {
			if (f[i]) {
				chmin(ans, 1);
			}
		}
		if (x[i] == n - 1 || y[i] == 0) {
			if (f2[i]) {
				chmin(ans, 1);
			}
		}
	}
	dump(ans);

	//????????????
	//q = queue<int>();
	//q2 = queue<int>();

	rep(i, 0, k) {
		if (x[i] == n - 1 || y[i] == 0) {
			q.emplace(i);
		}
	}

	memset(f, 0, sizeof(f));
	memset(tmp, 0, sizeof(tmp));
	while (q.size()) {
		int idx = q.front(); q.pop();
		if (f[idx])continue;
		f[idx] = true;
		rep(dx, -1, 2)rep(dy, -1, 2) {
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (mp.find(P(nx, ny)) == mp.end())continue;
			int nidx = mp[P(nx, ny)];
			if (f[nidx])continue;
			q.emplace(nidx);
		}
		rep(dx, -2, 3)rep(dy, -2, 3) {
			if (max(abs(dx), abs(dy)) <= 1)continue;
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (mp.find(P(nx, ny)) == mp.end())continue;
			int nidx = mp[P(nx, ny)];
			if (f[nidx])continue;
			if (tmp[nidx])continue;
			tmp[nidx] = true;
			q2.emplace(nidx);
		}
	}
	memset(f2, 0, sizeof(f2));
	while (q2.size()) {
		int idx = q2.front(); q2.pop();
		if (f2[idx])continue;
		f2[idx] = true;
		rep(dx, -1, 2)rep(dy, -1, 2) {
			int nx = x[idx] + dx, ny = y[idx] + dy;
			if (!inrange(nx, ny))continue;
			if (!mp.count(P(nx, ny)))continue;
			int nidx = mp[P(nx, ny)];
			if (f2[nidx])continue;
			q2.emplace(nidx);
		}
	}

	rep(i, 0, k) {
		if (x[i] == 0 || y[i] == m - 1) {
			if (f[i]) {
				chmin(ans, 0);
			}
		}
	}
	rep(i, 0, k) {
		if (x[i] == 1 || y[i] == m - 2) {
			if (f[i]) {
				chmin(ans, 1);
			}
		}
		if (x[i] == 0 || y[i] == m - 1) {
			if (f2[i]) {
				chmin(ans, 1);
			}
		}
	}

	cout << ans << endl;
	return 0;
}

Measured memory_bytes: 10404