#include <iostream>
#include <fstream>
using namespace std;
ifstream f("operatii.in");
ofstream g("operatii.out");
 long long  n,sum,v[1000001];

int main()
{f>>n;
 for(int i=1;i<=n;i++)f>>v[i];
 for(int i=0;i<=n;i++)
  if(v[i+1]-v[i]>0)sum+=v[i+1]-v[i];
 g<<sum;
    return 0;
}