#include <stdio.h>
#include <math.h>

long nr, n, i, v[1000010], x;

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