n,m = map(int, input().split())

if m > 1 and n > 1:
    if m == n:
        print((n-1)+((m-1)*n))
    elif m > n:
        print((n-1)+((m-1)*n))
    else:
        print((m-1)+((n-1)*m))
elif m == 1:
    print(n-1)
elif n == 1:
    print(m-1)
else:
    print(0)