#include<stdio.h>
#define dim 1000005
using namespace std;
long long int n,i,maxf,v[dim],x;
int main()
{
 FILE *f=fopen("operatii.in","r"), *g=fopen("operatii.out","w");
 
 fscanf(f,"%lld",&n);
  for(i=1;i<=n;i++)
   {fscanf(f,"%lld",&v[i]);
	if(v[i]>v[i-1]) maxf+=v[i]-v[i-1];
   }

fprintf(g,"%lld\n",maxf);
fclose(f);
fclose(g);
return 0;
}