# Enter your code here. Read input from STDIN. Print output to STDOUT

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

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