void main() {
	const W = readInt;
	const H = readInt;
	const N = readInt;
	auto S = new int[N];
	auto K = new int[N];
	foreach (i; 0 .. N) {
		S[i] = readInt;
		K[i] = readInt;
	}
	K.sort;
	int ans;
	int h = H;
	for (int i = 0; i < N;) {
		int j = i;
		while (j < N && K[i] == K[j]) j++;
		ans += W - (j - i);
		h--;
		i = j;
	}
	ans += cast(int)(S.sort.uniq.array.length) * h;
	ans.writeln;
}

import std,core.bitop;
string[]_R;
string readString(){while(_R.empty){_R=readln.chomp.split;}auto ret=_R.front;_R.popFront;return ret;}
int readInt(){return readString.to!int;}
long readLong(){return readString.to!long;}
ulong readULong(){return readString.to!ulong;}
real readReal(){return readString.to!real;}
bool chmin(T)(ref T A,T B){if(A>B){A=B;return true;}else{return false;}}
bool chmax(T)(ref T A,T B){if(A<B){A=B;return true;}else{return false;}}
int lowerBound(T)(T[]A,T x){int L=-1,R=cast(int)A.length;while(R-L>1){int mid=(L+R)/2;(A[mid]<x?L:R)=mid;}return R;}
int upperBound(T)(T[]A,T x){int L=-1,R=cast(int)A.length;while(R-L>1){int mid=(L+R)/2;(A[mid]<=x?L:R)=mid;}return R;}