# include <fstream>
# include <iostream>
# include <cstdlib>
using namespace std;
int n, v[1000003], u[1000003], m;

void read ()
{
	ifstream fin ("operatii.in");
	fin>>n;
	for (int i=1;i<=n;i++)
	{
		fin>>u[i];
		if (u[i]>u[i-1])
			v[++m]=i;
	}
}

void solve ()
{
	long long int sol=0;
	for (int i=1;i<=m;i++)
		sol+=u[v[i]]-u[v[i]-1];
	ofstream fout ("operatii.out");
	fout<<sol;
}
				
int main ()
{
	read ();
	solve ();
	return 0;
}