#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
 
int min(int x, int y) { return x < y ? x : y; }
int max(int x, int y) { return x > y ? x : y; }
 
int maxProfit(int* prices, int pricesSize) {
    int *dp = malloc((pricesSize+1)*sizeof(int)), ans = 0;
    dp[pricesSize] = INT_MIN;
	for (int i = pricesSize-1; i >= 0; --i)
		dp[i] = max(dp[i+1],prices[i]);
    for (int b = INT_MAX, i = 1; i < pricesSize; ++i)
    	b = min(b,prices[i-1]), ans = max(ans,dp[i] -= b);
    free(dp);
    return ans; }
 
int main(void) {
	int *prices, pricesSize;
	scanf("%d",&pricesSize), prices = malloc(pricesSize*sizeof(int));
	for (int i = 0; i < pricesSize; ++i)
		scanf("%d",prices+i);
	printf("%d",maxProfit(prices,pricesSize)), free(prices);
	return 0; }
 

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