#include<fstream>
using namespace std;
int vector[1000003];
int main()
{
	ifstream fi("operatii.in");
	ofstream fo("operatii.out");

	int n,cont=0;
	
	fi>>n;
	
	for(int i=1; i<=n; i++)
		fi>>vector[i];
	
	for(int i=1; i<n; i++)
	{
		if(vector[i]<vector[i+1])
		{
			cont+=(vector[i+1]-vector[i]);
		}
	}
	
	
	fo<<cont;
	
	fi.close();
	fo.close();
	
	return 0;
}