#include<fstream>
using namespace std;
unsigned int n,i,j,x,max1,nrmin,ok,p;
int main()
{
	ifstream f("operatii.in");
	ofstream g("operatii.out");
	f>>n;
	for(i=1;i<=n;i++)
	{
		f>>x;
		if(x>p)
			nrmin+=x-p;
		p=x;
	}
	g<<nrmin<<"\n";
	return 0;
}