DP

#include<bits/stdc++.h>
using namespace std;

int maxProfit(int* prices, int pricesSize){
    if(pricesSize <= 1) return 0;
    int i = 0,* _prices,max;
    _prices = (int *)malloc(sizeof(int) * pricesSize);
    _prices[0] = 0;
    if(prices[1] - prices[0] > 0) max = _prices[1];else max = 0;
    for(i = 1;i<pricesSize;i++){
        _prices[i] = prices[i] - prices[i-1];
        if(_prices[i - 1] > 0)_prices[i] += _prices[i - 1];
        if(_prices[i] > max)max = _prices[i];
    }

    free(_prices);
    return max;
}

int main(void){
    int pricesSize;
    cin >> pricesSize;
    int prices[pricesSize];
    for(int i = 0;i < pricesSize;i ++)
        cin >> prices[i];
    cout << maxProfit(prices,pricesSize);
}