#include<cstdio>

#include<cstring>

#include<cmath>

#include<string>

#include<vector>

#include<queue>

#include<algorithm>

#include<iostream>

using namespace std;

const int maxn =  + ;

int n, m;

int a[maxn];

int b[maxn];

int flag[maxn];

int topa, topb;

int main()

{

    scanf("%d%d", &n, &m);

    memset(a, , sizeof a);

    memset(b, , sizeof b);

    memset(flag, , sizeof flag);

    int num1 = , num2 = , num;

    int nowa = , nowb = ;

    for (int aa = , i = ; aa < n; i = i + )

    {

        if (i %  != ) a[i] = , topa = i, aa++;

        else nowa = i;

    }

    for (int aa = , i = ; aa<m; i = i + )

    {

        if (i %  != ) b[i] = , topb = i, aa++;

        else nowb = i;

    }

    while ()

    {

        if (nowa ==  && nowb == ) break;

        if (topa>topb)

        {

            a[topa] = ; topa--;

            while ()

            {

                if (b[nowa] == )

                {

                    a[nowa] = ;

                    nowa = nowa - ;

                    while ()

                    {

                        if (a[topa]) break;

                        topa--;

                    }

                    break;

                }

                nowa = nowa - ;

            }

        }

        else

        {

            b[topb] = ; topb--;

            while ()

            {

                if (a[nowb] == )

                {

                    b[nowb] = ;

                    nowb = nowb - ;

                    while ()

                    {

                        if (b[topb]) break;

                        topb--;

                    }

                    break;

                }

                nowb = nowb - ;

            }

        }

        while ()

        {

            if (b[nowa]) nowa = nowa - ;

            else break;

        }

        while ()

        {

            if (a[nowb]) nowb = nowb - ;

            else break;

        }

    }

    printf("%d\n", max(topa, topb));

    return ;

}