#include<stdio.h>

long long a[1000004],i,n,k;

int main()
{	freopen("operatii.in","r",stdin);
	freopen("operatii.out","w",stdout);
	scanf("%lld%lld",&n);
	for(i=1;i<=n;i++)
	{	scanf("%lld",&a[i]);
		if(a[i]>a[i-1]) k+=a[i]-a[i-1];
	}
	printf("%lld",k);
}