#include <stdio.h>
FILE *f=fopen("operatii.in","r");
FILE *g=fopen("operatii.out","w");
unsigned long long mx,nr,x1,x2,i,n;
int ok=1;
int main()
 {
 fscanf(f,"%lld",&n);
 fscanf(f,"%lld",&x1);
 mx=x1;
 for(i=2;i<=n;i++)
  {
  fscanf(f,"%lld",&x2);
  if(x1<x2)
   mx+=x2-x1;
  x1=x2;
  }
 fprintf(g,"%lld",(nr+mx));
 fclose(f);
 fclose(g);
 return 0;
 }