n,m=[int(x) for x in input().split()]

if n==1 and m==1:
    print(0)
elif n==1:
    print(m-1)
elif m==1:
    print(n-1)
else:    
    a=(max(n,m)-1)
    b=(min(n,m)-1)
    print (a+ b*max(n,m))