#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int mincut(long int n,long int m){
    
    if((n==1)&&(m==1))
        return 0;
    if(((n==2)&&(m==1))||((n==1)&&(m==2)))
        return 1;
    if(n>m)
        return (1+mincut(n-1,m));
    else if(m>=n)
        return (1+mincut(n,m-1));

   else
       return 0;
 }

int main() {
    long int n,m,cuts,i;
    cin>>n>>m;
    cuts=mincut(n,m);
    cout<<cuts;
    return 0;
}