#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,y,B,t;
	cin>>x>>y;
	B=1;
	B=2;
	if((y-x)%2==0){
		t = (y-x)/2;
		cout<<t<<' ';
	}
	else if((y-x)%2==1){{
			t=(y-x)/2;
			cout<<t+1<<' ';
		}
	}
	return 0;
}