#include <stdio.h>


 long a[1001002],n,i;
 long p;

 int main()
  {FILE *fin,*fout;


  fin=fopen("operatii.in","r");
  fscanf(fin,"%ld",&n);
  for (i=1;i<=n;i++)
       fscanf(fin,"%ld",&a[i]);
  fclose(fin);

  p=0;
  a[0]=0;
  for (i=1;i<=n;i++)
     if (a[i]>a[i-1]) p+=a[i]-a[i-1];


  fout=fopen("operatii.out","w");
  fprintf(fout,"%ld\n",p);
  fclose(fout);

  return 0;
  }