#include<iostream> using namespace std; int main(){ int n; cin>>n; int a[n+5]; for(int i=1;i<=n;i++){ cin>>a[i]; } int sum=0; for(int i=1;i<=n-1;i++){ if(a[i+1]>a[i]) sum=sum+a[i+1]-a[i]; } cout<<sum<<endl; return 0; }