#include<stdio.h>
long long n,s;
long long v[1000002];
int main()
{
	freopen("operatii.in","r",stdin);
	freopen("operatii.out","w",stdout);
	scanf("%lld",&n);
	long long i;
	for(i=1;i<=n;i++)
	{
		scanf("%lld",&v[i]);
		if(v[i]>v[i-1])
			s=s+v[i]-v[i-1];
	}
	printf("%lld",s);
	return 0;
}