#include <fstream>
#include <cstring>
#include <algorithm>
using namespace std;

ifstream fi("operatii.in");
ofstream fo("operatii.out");


long long x,y,n,i,j,s,k,poz,mini;
int a[1000005],fr[1000005];
bool ok;


int main()
{
  fi>>n;
  for(i=1;i<=n;i++)
    fi>>a[i];
  for(i=2;i<=n;i++){
    if(a[i]>a[i-1])k+=a[i]-a[i-1];
  }
  fo<<k;








    return 0;
}