import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
       //这里直接用贪心 当后边的数比前面大就直接买进然后卖出再买进再对比
       int cur =0,pre=1000000;
       int n = in.nextInt();
       int ret=0;
       while(n-->0){
        cur = in.nextInt();
        if(cur>pre){
           ret+=cur-pre;
        }
        pre = cur;
       }
       System.out.print(ret);
    }
}