#include <iostream>
#include <fstream>

using namespace std;

int main()
{    ifstream f("tabela.in");
     ofstream g("tabela.out");
     unsigned long long  l,c,max1,max2,i,j;
     int v[1000][1000];

    f>>l>>c;
    v[1][1]=0;
    for(i=2;i<=l;i++)
    {     v[i][1]=v[i-1][1]+1;
         for(j=2;j<=c;j++)
           {
            v[1][j]=v[1][j-1]+1;
            max1=v[i-1][j];
            max2=v[i][j-1];
            if(max1=max2) v[i][j]=max1-1;
           if(max1>max2)v[i][j]=max1+1;
           else v[i][j]=max2+1;
           }
    }

   g<<v[l][c];
   f.close();
   g.close();
    return 0;
}