#include <fstream>
using namespace std;
ifstream f("operatii.in");
ofstream g("operatii.out");
unsigned long long n,i,op;
int v[1000002];
int main()
{   f>>n;
    for(i=1;i<=n;i++)
      f>>v[i];
    for(i=1;i<=n;i++)
      if(v[i]>v[i-1]) op+=v[i]-v[i-1];
    g<<op;
    f.close();g.close();
    return 0;
}