#include <fstream>
using namespace std;

ifstream f("operatii.in");
ofstream g("operatii.out");

int i,x,y;
long long n;
unsigned long long nr;

int main()
{f>>n;
f>>x;
	nr=nr+x;
	
for (i=1;i<n;i++)
	{f>>y;
	if(y>x)
		nr=nr+(y-x);
	x=y;
	}
	g<<nr;
	



	return 0;
}