#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
const int MAX_SIZE = 100000;

int main() {
    int N, win = 0;
    cin >> N;
    int arr[MAX_SIZE];
    for (int i=0; i < N; i++){
        cin >> arr[i];
    }
    for (int i=0; i < N - 1; i++){
        if (arr[i] < arr[i+1]) {win += (arr[i+1]-arr[i]);}
    }
    cout << win;
    return 0;
}