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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    long long int n,m,ans;
    scanf("%lld%lld",&n,&m);
    ans=(n+m)/2;
    printf("%lld\n",ans);
    
    return 0;
}