#include <stdio.h>
int e[1000005];
int main()
{
	long long n,a,i,j,d;
	FILE *f1,*f2;
	f1=fopen("operatii.in","r");
	f2=fopen("operatii.out","w");
	for(i=0;i<=1000004;i++)
	{
		e[i]=0;
	}
	fscanf(f1,"%lld\n",&n);
	for(i=1;i<=n;i++)
	{
		fscanf(f1,"%lld ",&a);
		if(a>=0 && a<=100000)
		{
			e[i]=a;
		}

	}
	d=e[1];
	for(i=1;i<=n-1;i++)
	{
		if(e[i]<e[i+1])
			d=d+e[i+1]-e[i];
	
	}
	fprintf(f2,"%lld",d);
	fclose(f1);
	fclose(f2);

	return 0;
}