n, m = map(int, raw_input().strip().split(' '))

if n == 1 and m == 1:
    res = 0

elif n > 1 and m == 1:
    res = n - 1

elif m > 1 and n == 1:
    res = m - 1

elif m > 1 and n > 1:
    res = m - 1 + n - 1

print res