# Enter your code here. Read input from STDIN. Print output to STDOUT
m, n = map(long, raw_input().split())
import sys
def divide(m, n, memory):
    key = str(m) + "_" + str(n)
    if key in memory: return memory[key]
    
    if m == 1 and n == 1:
        memory[key] = 0
        return memory[key]
    elif (m == 2 and n == 1) or (m == 1 and n == 2):
        memory[key] = 1
        return memory[key]
    
    ret = sys.maxint
    for i in xrange(1, m):
        ret = min(ret, divide(i, n, memory) + divide(m-i, n, memory) + 1)
    
    for i in xrange(1, n):
        ret = min(ret, divide(m, i, memory) + divide(m, n-i, memory) + 1)
    
    memory[key] = ret
    return ret


def divideDp(m, n):
    dp = [[long(0) for i in xrange(n+1)] for j in xrange(m+1)]

    for i in xrange(1, n+1):
        dp[1][i] = i-1

    for i in xrange(1, m+1):
        dp[i][1] = i-1

    for i in xrange(2, m+1):
        for j in xrange(2, n+1):
            row, col, val = i, j, sys.maxint
            for k in xrange(1, row):
                val = min(val, dp[k][col] + dp[row-k][col] + 1)

            for k in xrange(1, col):
                val = min(val, dp[row][k] + dp[row][col-k] + 1)
            dp[i][j] = val

    return dp[m][n]

print min(m-1+(n-1)*m, n-1+(m-1)*n)

#print divide(m, n, {})