//
//  main.cpp
//  operatii
//
//  Created by Eusebiu Rares on 07/04/2020.
//  Copyright © 2020 Eusebiu Rares. All rights reserved.
//

#include <iostream>
#include "fstream"

std::fstream in ("operatii.in", std::ios::in) ;
std::fstream out ("operatii.out", std::ios::out) ;

typedef long long i64 ;

int main(int argc, const char * argv[]) {
	int n, first, second ; in >> n >> first ;
	i64 answer(first) ;
	for (int i = 1 ; i <= n - 1 ; ++ i) {
		in >> second ;
		answer += std::max(0, second - first) ;
		first = second ;
	}
	out << answer ;
}