AC

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;
	vector<int> d(n);
	for (int i = 0; i < n; i++) {
		cin >> d[i];
	}

	int days = 0;
	int prev = 0;

	for (int i = 0; i < n; i++) {

		if (d[i] > prev) {
			days += d[i] - prev;
		}
		prev = d[i];
	}

	cout << days << endl;
	return 0;
}