def bishop(H, W):
    if H==1 or W== 1:
        return 1
    result  = int((H-1)/2 + 1) * int((W-1)/2 + 1) + int(H/2) * int(W/2)
    return result
ans = input().split(" ")
H = int(ans[0])
W = int(ans[1])
print(bishop(H,W))
