#include<bits/stdc++.h> using namespace std; int a[1010]; int main(){ int n; scanf("%d",&n); for(int i = 0;i < n;i++){ scanf("%d",&a[i]); } int sum = 0; for(int i = 0;i < n-1;i++){ if(a[i+1] - a[i] > 0){ sum+=(a[i+1] -a[i]); }else{ continue; } } printf("%d",sum); return 0; }