#include<fstream.h>
ifstream in("operatii.in");
ofstream out("operatii.out");
int n;
long long int k,v[1000000];
int main()
{	int i,j;
	in>>n;
	for(i=1;i<=n;i++)
		in>>v[i];
	in.close();
	v[0]=0;
	for(i=1;i<=n;i++)
		if(v[i]>v[i-1])k=k+(v[i]-v[i-1]);	
	out<<k;
	out.close();
	return 0;
}