#include <stdio.h>
#include <vector>
#include <algorithm>
#include <math.h>
 
using namespace std;

int n;
 
int main() {
	freopen("operatii.in", "r", stdin);
	freopen("operatii.out", "w", stdout);

	scanf("%d", &n);

	int last = 0;

	int64_t res = 0;

	for (int i = 0; i < n; ++i) {
		int x;
		scanf("%d", &x);

		if (x > last) {
			res += x - last;
		}

		last = x;
	}

	printf("%lld", res);

	return 0;
}