H, W, Q = map(int, input().split()) ans = H * W giant = {} from bisect import bisect for i in range(Q): y, x = map(int, input().split()) if giant.get(x, -1) == -1: giant[x] = y ans -= H + 1 - y else: if giant[x] > y: ans -= giant[x] - y giant[x] = y print(ans)