#include<stdio.h>
FILE*fin=fopen("operatii.in","r");
FILE*fout=fopen("operatii.out","w");
int main()
{
  long long rez=0;
  int nr,ant=0,n,i;
  fscanf(fin,"%d",&n);
  for(i=1;i<=n;i++)
  {
    fscanf(fin,"%d,",&nr);
    if(nr<ant) rez+=(ant-nr);
    ant=nr;
  }
  rez+=ant;
  fclose(fin);
  fprintf(fout,"%lld",rez);
  fclose(fout);
  return 0;
}