#include <bits/stdc++.h>

#include <atcoder/modint>

#include <algorithm>
#include <cassert>
#include <vector>

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 (a > b) {
        a = b;
        return true;
    }
    return false;
}

template <class T>
T div_floor(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a >= 0 ? a / b : (a + 1) / b - 1;
}

template <class T>
T div_ceil(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a > 0 ? (a - 1) / b + 1 : a / b;
}

template <typename T>
struct CoordComp {
    std::vector<T> v;
    bool sorted;

    CoordComp() : sorted(false) {}

    int size() { return v.size(); }

    void add(T x) { v.push_back(x); }

    void build() {
        std::sort(v.begin(), v.end());

        v.erase(std::unique(v.begin(), v.end()), v.end());
        sorted = true;
    }

    int get_idx(T x) {
        assert(sorted);
        return lower_bound(v.begin(), v.end(), x) - v.begin();
    }

    T &operator[](int i) { return v[i]; }
};


#define For(i, a, b) for (int i = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int i = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For(i, 0, n)
#define rrep(i, n) rFor(i, n, 0)
#define fi first
#define se second

using namespace std;

using lint = long long;
using pii = pair<int, int>;
using pll = pair<lint, lint>;

using namespace atcoder;
using mint = modint1000000007;

int dp[1010][1010];
bool ok[1010][1010];

int main() {
    int n, m, q;
    scanf("%d%d%d", &n, &m, &q);
    rep(i, q) {
        int a, b;
        scanf("%d%d", &a, &b);
        --a;
        --b;
        ok[a][b] = true;
    }

    rep(i, n + 1) rep(j, m + 1) {
        if (i < n) chmax(dp[i + 1][j], dp[i][j]);
        if (j < m) chmax(dp[i][j + 1], dp[i][j]);
        if (i < n && j < m && ok[i][j]) chmax(dp[i + 1][j + 1], dp[i][j] + 1);
    }
    printf("%d\n", dp[n][m]);
}