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

inputs = $stdin.read.split()
n = inputs[0].to_i
m = inputs[1].to_i


def num_cuts(n,m)
    paper_size = n*m
    num_cuts = paper_size - 1
    return num_cuts
    #inputs.class
end

print num_cuts(n,m)