def main():
    import sys
    input = sys.stdin.readline
    W = int(input())
    H = int(input())
    N = int(input())
    SK = [list(map(int,input().split())) for _ in range(N)]

    d1 = set()
    d2 = set()
    s = set()

    for i in range(N):
        S,K = SK[i]
        s.add((S,K))
        d1.add(S)
        d2.add(K)
    
    count = 0
    count += (H-len(d2))*len(d1)
    count += (W-len(d1))*len(d2)

    for i in d1:
        for j in d2:
            if not (i,j) in s:
                count += 1
    print(count)




if __name__ == '__main__':
    main()