#include <bits/stdc++.h>
using namespace std;
using db = long double;
using ll = long long;
using pl = pair<ll, ll>;
using pi = pair<int, int>;
#define vt vector
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(), x.end()
#define size(x) ((int) (x).size())
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define F0R(i, b) FOR (i, 0, b)
#define endl '\n'
const ll INF = 1e18;
const int inf = 1e9;
template<typename Tuple, size_t... Is>
void print_tuple(const Tuple& t, index_sequence<Is...>) {
((cerr << (Is == 0 ? "{" : ", ") << get<Is>(t)), ...);
cerr << "}";
}
template<typename... Args>
ostream& operator<<(ostream& os, const tuple<Args...>& t) {
print_tuple(t, index_sequence_for<Args...>{});
return os;
}
ostream& operator<<(ostream& os, string& s) {
for (char c : s) os << c;
return os;
}
template<template<typename> class Container, typename T>
ostream& operator<<(ostream& os, Container<T> o) {
os << "{";
int g = size(o);
for (auto i : o) os << i << ((--g) == 0 ? "" : ", ");
os << "}";
return os;
}
template<typename T, typename V>
ostream& operator<<(ostream& os, const pair<T, V> p) {
os << "{" << p.f << ", " << p.s << "}";
return os;
}
template <typename T, typename... V>
void printer(const char *names, T &&head, V &&...tail) {
int i = 0;
while (names[i] != '\0' && names[i] != ',') i++;
constexpr bool is_str = is_same_v<decay_t<T>, const char*>;
if constexpr (is_str) cerr << head; // ignore directly passed strings
else cerr.write(names, i) << " = " << head;
if constexpr (sizeof...(tail)) cerr << (is_str ? "" : ","), printer(names + i + 1, tail...);
else cerr << endl;
}
#ifdef LOCAL
#define dbg(...) std::cerr << __LINE__ << ": ", printer(#__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(x...)
#define cerr if (0) std::cerr
#endif
/*
range perfect matching goes crazy
since kuhn's is more efficient when lhs is small, we need the girls to be on the left
we want to find the maximum r for each l, and two pointer it
*/
int n, m, k; // n is lhs (girls), m is rhs (boys)
vt<vt<int>> adj; // l -> r
vt<int> mni; // index of first neighbour we iterate over
vt<int> mate; // mate = rhs -> lhs
bool seen[2001]; // seen of lhs
bool dfs(int u) {
if (seen[u]) return false;
seen[u] = true;
FOR (i, mni[u], size(adj[u])) {
int v = adj[u][i];
if (mate[v] == -1 || dfs(mate[v])) {
mate[v] = u;
return true;
}
}
return false;
}
main() {
cin.tie(0)->sync_with_stdio(0);
cin >> m >> n >> k;
adj.resize(n);
mni.resize(m);
mate.resize(m, -1);
vt<pi> edges;
vt<vt<int>> radj(m);
F0R (i, k) {
int u, v; cin >> u >> v; u--, v--;
// u is boy, v is girl
radj[u].pb(v);
}
int r = 0, matches = 0;
vt<int> mxr(m, m + 1); // exc
queue<int> to_match;
F0R (i, n) to_match.push(i);
F0R (l, m) {
while (size(to_match)) {
if (r == m) break;
// add these edges
for (int u : radj[r]) adj[u].pb(r);
// try augment
int u = to_match.front();
memset(seen, 0, sizeof(seen));
while (dfs(u)) {
to_match.pop();
if (!size(to_match)) break;
u = to_match.front();
memset(seen, 0, sizeof(seen));
}
r++;
}
if (size(to_match)) break;
mxr[l] = r;
// remove edges
for (int u : radj[l]) {
mni[u]++;
}
// check if we unmatched someone
if (mate[l] != -1) {
to_match.push(mate[l]);
mate[l] = -1;
}
}
ll ans = 0;
F0R (i, m) ans += m - mxr[i] + 1;
cout << ans << endl;
}
