#include <bits/stdc++.h> using namespace std; const int N = 1e6 + 005; int a[N], d[N]; int main() { int n, maxn = 0; cin >> n; for (int i = 1; i <= n; i++) cin >> a[i]; for (int i = 1; i < n; i++) maxn += (a[i] < a[i + 1] ? a[i + 1] - a[i] : 0); cout << maxn << endl; return 0; }