#include <fstream>
using namespace std;
ifstream fi("operatii.in");
ofstream fo("operatii.out");
int sol,a,b,i,n;
int main()
{ fi>>n;
  for(i=1;i<=n;i++)
  { fi>>a;
    if(a>b) sol+=a-b;
    b=a;
  }
 fo<<sol;
    return 0;
}