#include<stdio.h>


int main()
{
	FILE *f=fopen("operatii.in","r");
	
  	int i,n,v[1000000];
	long long nr;

	fscanf(f,"%i",&n);

	for(i=0;i<n;i++)
	fscanf(f,"%i",&v[i]);


	nr=v[0];



	for(i=0;i<n-1;i++)
	{
	if(v[i+1]>v[i])
	nr+=v[i+1]-v[i];
	}


	fclose(f);

	f=fopen("operatii.out","w");
	fprintf(f,"%lli",nr);
	fclose(f);
	return 0;

}