#include <iostream>
#include <fstream>

using namespace std;

int main() {
long long n, i, s, x, maxim;
s = 0;
ifstream in ("operatii.in");
ofstream out ("operatii.out");
in >> n;

maxim = 0;
for(i = 0 ;i < n; i++)
{	
	in >> x;
	if(x > maxim)
	s = s + x - maxim;
	maxim = x;
}
out << s;
return 0;
}