#include <bits/stdc++.h>
using namespace std;
const int N = 1000000 + 10;
long long n,a[N];
long long maxn[N],minn[N];
long long ans;
int main(){
	scanf("%lld",&n);
	for(int i = 1; i <= n; i++){
		scanf("%lld",&a[i]);
	}
	maxn[n] = a[n];
	for(int i = n - 1; i >= 1; i--){
		maxn[i] = max(maxn[i + 1],a[i]);
	}
	minn[1] = a[1];
	for(int i = 2; i <= n; i++){
		minn[i] = min(minn[i - 1],a[i]);
	}
	for(int i = 1; i < n; i++){
		ans = max(ans,maxn[i + 1] - minn[i]);
	}
	printf("%lld\n",ans);
	return 0;
}



......有神犇帮忙看看嘛，86分，两个点wa了