#include <iostream>
#include <fstream>
using namespace std;
ifstream in("operatii.in");
ofstream out("operatii.out");
const int maxn = 1000005;
int v[maxn];
int main()
{
    int n;
    in >> n;
    for(int i = 1; i <= n; i++)
        in >> v[i];
    int s = 0;
    for(int i = 2; i <= n; i++)
        if(v[i] - v[i-1] > 0)
            s = s + v[i] - v[i-1];
    out << s << "\n";
    return 0;
}