#include <fstream>

using namespace std;

ifstream fin( "operatii.in" );
ofstream fout( "operatii.out" );   

int main() {
  int n, x, y;
  long long res = 0;

  fin >> n >> x;
  res += x;
  for ( int i = 2; i <= n; ++i ) {
	fin >> y;
	res += (x < y ? y - x : 0);
    x = y;
  }
  fout << res;
  fin.close();
  fout.close();
  return 0;
}