86分，测试点12和13一直WA？

#include<iostream>
using namespace std;
long long a[1000001];
int main()
{
	int n;
	cin>>n;
	long long ans=0;
	long long minn=999999999999999;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
		ans=max(ans,a[i]-minn);
		minn=min(minn,a[i]);
	}
	cout<<ans;
	return 0;
}