#include #include #include #include #include #include #include #include #include #include #include using namespace std; #define int long long #define FOR(i, a, b) for(int i=(a);i<(b);i++) #define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--) #define REP(i, n) for(int i=0; i<(n); i++) #define RREP(i, n) for(int i=(n-1); i>=0; i--) #define ALL(a) (a).begin(),(a).end() #define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end()); #define CONTAIN(a, b) find(ALL(a), (b)) != (a).end() #define SUM(a) accumulate(ALL(a), 0) #define array2(type, x, y) array, x> #define vector2(type) vector > #define out(...) printf(__VA_ARGS__) typedef pair pos; int pos::*x = &pos::first; int pos::*y = &pos::second; int dxy[] = {0, 1, 0, -1, 0}; /*================================*/ int W, H, N, S, K; signed main() { cin >> W >> H >> N; set ss; set ks; REP(i,N) { cin >> S >> K; ss.insert(S); ks.insert(K); } int scnt = ss.size() * H; int kcnt = ks.size() * W; int dcnt = ss.size() * ks.size(); cout << scnt + kcnt - dcnt - N << endl; return 0; }