#include <stdio.h>

int main(void){
	int num = 0;
	scanf("%d",&num);
	
	int val[num];
	int *p = val;
	for(int i = 0;i < num;i++){
		scanf("%d",&p[i]);
		printf("%d\n",p[i]);
	}
	double ans = 0;
	int res = num / 2;
	for(int i = 0;i < num;i++){
		if(res == i){
			if(num % 2 == 0){
				ans = (val[i] + val[i - 1]) / 2;
				printf("偶数の場合の合計%d\n",val[i] + val[i - 1]);
			}else{
				ans = val[i];
			}		
		}
	}
	printf("%lf",ans);
	
}