#include<fstream>
#include<algorithm>
#include<vector>
#include dll long long
using namespace std;

long long n,v[1000005],a,b;

int main()
{
	ifstream f("operatii.in");
	ofstream g("operatii.out");
	f>>n;
	int dif,i;
	dll contor=0;
	for(i=1;i<=n;i++)
	{
		f>>a;
		if(a>b)
		{
			dif=a-b;
			contor=contor+dif;
		}
		b=a;
	}
	g<<contor;
	f.close();
	g.close();
	return 0;
}