#include <iostream>
#include <cstdio>

using namespace std;

long long N , cont = 0 , x[1000005];

int main ()
{
	freopen ("operatii.in" , "r" , stdin);
	freopen ("operatii.out" , "w" , stdout);
	
	scanf ("%lld" , &N);
	
	for (long long i = 1 ; i <= N ; ++i)
	{
		scanf ("%lld" , &x[i]);
		
		if (x[i] > x[i - 1])
			cont += x[i] - x[i - 1];
		
	}
	
	printf ("%lld" , cont);
	
	return 0;
}