var str = read_line();
	

	

		var arr = str.split(' ');
	

	

		//转为整数
	

	

		arr = arr.map(function(item,index){
	

	

		return +item;
	

	

		});
	

	

		//排序
	

	

		arr.sort(function(a,b){return a- b});
	

	

		var mid = arr.length % 2 == 0 ? (arr[Math.floor(arr.length / 2) - 1] + arr[Math.floor(arr.length / 2)]) / 2 : arr[Math.floor(arr.length / 2)];
	

	

		print(mid);