#include<bits/stdc++.h>
using namespace std;
signed main(){
	long long n,zd;
    cin >> n;
    long long dp[n+1];
    for(int i = 1;i <= n;++i){
    	dp[i] -= 1e18;
	}
    for(int i = 1;i <= n;++i){
    	long long x;
    	cin >> x;
    	for(int j = i;j >= 0;--j){
			dp[j] = max(dp[j - 1] + j * x,dp[j]);
    	}
	}
	
    for(int i = 1;i <= n;++i){
		zd = max(zd,dp[i]);
	}
	
	cout << zd;
	return 0;
}

请帮我看看，谢谢！