#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;} template inline string toString(T x) {ostringstream sout;sout< VI; typedef vector VVI; typedef vector VS; typedef pair PII; typedef long long LL; #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define ALL(a) (a).begin(),(a).end() #define RALL(a) (a).rbegin(), (a).rend() #define PB push_back #define MP make_pair #define SZ(a) int((a).size()) #define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i) #define EXIST(s,e) ((s).find(e)!=(s).end()) #define SORT(c) sort((c).begin(),(c).end()) const double EPS = 1e-10; const double PI = acos(-1.0); #define CLR(a) memset((a), 0 ,sizeof(a)) #define dump(x) cerr << #x << " = " << (x) << endl; #define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl; int main() { cin.tie(0); ios::sync_with_stdio(false); unsigned long long W, H, N; cin >> W >> H >> N; set S, K; REP(i, N){ int tmp1, tmp2; cin >> tmp1 >> tmp2; S.insert(tmp1); K.insert(tmp2); } unsigned long long ret = (unsigned long long)W * H; ret -= W * K.size(); ret -= H * S.size(); ret += S.size() * K.size(); cout << W * H - ret - N << endl; return 0; }