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)]
    count = 0
    for i in range(N):
        count += W - 1
        count += H - 1
    
    for i in range(N):
        for j in range(i+1,N):
            if SK[i][0] == SK[j][0]:
                count -= H - 1
                count -= 1
            elif SK[i][1] == SK[j][1]:
                count -= W - 1
                count -= 1
            else:
                count -= 1
    print(count)

if __name__ == '__main__':
    main()