#include <cstdio>
#include <algorithm>
using namespace std;

#define LL long long

int i, N;
int x, Vm;
LL ANS;

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