#include <fstream>   

using namespace std;

int n,a[1001000];
long int nr;   

void citire()   
{   
   ifstream fin("operatii.in");   
   fin>>n;   
   for (long i=0;i<n;i++)   
       fin>>a[i];   
   fin.close();   
}   
  
void numarare()   
{   
 for (int j=0;j<n;j++){   
   if (a[j]>a[j-1])   
      nr+=a[j]-a[j-1];     
  }
}   
  
int main()   
{   
   citire();   
   numarare();   
   ofstream fout("operatii.out");   
   fout<<nr<<"\n";   
   fout.close();   
   return 0;   
  
}