/** made by amunduzbaev **/
#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define ub upper_bound
#define lb lower_bound
#define ll long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(),x.rend()
#define fastios ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define vll vector<ll>
#define vii vector<int>
#define vpii vector<pii>
#define vpll vector<pll>
#define cnt(a)__builtin_popcount(a)
template<class T> bool umin(T& a, const T& b) {return a > b? a = b, true:false;}
template<class T> bool umax(T& a, const T& b) {return a < b? a = b, true:false;}
const int N = 5000;
const int mod = 1e9+7;
const ll inf = 1e18;
const ld Pi = acos(-1);
ll a[N], s, n, m, k, ans;
vector<vii> edges(N);
bool find(int u, int l, int r, vii used){
if(u == m) return 1;
bool ok = 0;
for(auto x : edges[u]){
if(used[x] || x < l || x > r) continue;
used[x] = 1;
ok |= find(u+1, l, r, used);
used[x] = 0;
}return ok;
}
void solve(){
cin>>n>>m>>k;
for(int i=0;i<k;i++){
int a, b; cin>>a>>b;
edges[--b].pb(--a);
// edges[a].pb(b);
}
for(int i=0;i<n;i++){
for(int j=i;j<n;j++){
vii tmp(n, 0);
ans += find(0, i, j, tmp);
//cout<<i<<" "<<j<<" "<<ans<<endl;
}
}cout<<ans<<endl;
return;
}
int main(){
fastios
int t = 0;
if(!t) solve();
else {
cin>>t;
while (t--) solve();
}
return 0;
}
