#include<cstdio>

FILE *fin=freopen("operatii.in","r",stdin),
     *fout=freopen("operatii.out","w",stdout);    

int a[100000000];
long n;

int main()
{
  scanf("%lld",&n);
  for(int i=1;i<=n;i++)
    scanf("%lld",&a[i]);
  long contor=0;
  for(int i=1;i<=n;i++)
  {
    if(a[i]>a[i-1]) contor=contor+(a[i]-a[i-1]);
    a[i-1]=a[i];
  }
  printf("%lld",contor);
}