#include<bits/stdc++.h>
using namespace std;

//#define ONLINE
#ifndef ONLINE
#define debug(...) fprintf(stderr,##__VA_ARGS__)
#else
#define debug(...) ;
#endif

using LL=long long;
using PII=pair<int,int>;

template<typename T>
inline T READ(){
	T x=0; bool f=0; char c=getchar();
	while(c<'0' || c>'9') f|=(c=='-'),c=getchar();
	while(c>='0' && c<='9') x=x*10+c-'0',c=getchar();
	return f?-x:x;
}
inline int read(){return READ<int>();}
inline LL readLL(){return READ<LL>();}
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());

void solve(){
	int n=read();
	LL ans=0;
	if(n==2){
		ans=read()/2+read()/2;
	}
	else{
		for(int i=0;i<n;i++){
			ans+=read();
		}
		ans>>=1;
	}
	cout<<ans;
}

int main(){
	solve();
	return 0;
}

/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
*/