凭什么洛谷提示我编译失败？

#include <iostream>
#include <queue>
#include <cmath>
using namespace std;
int n;
priority_queue<long long> d;
priority_queue<long long> x;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		long long a;
		cin>>a;
		if(i==1){
			cout<<a<<"\n";
			d.push(a);
		}
		else {
			if(a>d.top()){
				x.push(-a); 
			}
			else{
				d.push(a);
			}
			if(abs(x.size()-d.size())>=2){
				if(x.size()>d.size()){
					d.push(-x.top());
					x.pop(); 
				}
				else{
					x.push(-d.top());
					d.pop();
				}
			}
			if(i%2==1){
				if(d.size()>x.size()){
					cout<<d.top();
				}
				else{
					cout<<-x.top();
				}
				cout<<"\n";
			}
		}
	}
	return 0;
}