#include<stdio.h>
int n;
int main()
{
	int j,nr=0,p=0,q,w=0;
	freopen("operatii.in","r",stdin);
	freopen("operatii.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
	{
		scanf("%d",&q);
		if(q>w)
			nr=(nr-w)+q;
		w=q;
	}
	printf("%d",nr);
	return 0;
}