#include<iostream>
#include<algorithm>
using namespace std;
int price[100000],dp[100000] = {0};
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    for(int i = 0;i < n;++i)
        cin >> price[i];
    for(int i = 1;i < n;++i){ 
        int sum = price[i] - price[i - 1];
        if(sum > 0)
            dp[i] = dp[i - 1] + sum;
        else
            dp[i] = dp[i - 1];
    }
    cout << dp[n - 1];
}