#include <stdio.h>
int main()
{
	FILE *in,*out;
	long long  n,a,nr,x,i;
	in=fopen("operatii.in","r");
	out=fopen("operatii.out","w");
	fscanf(in,"%lld",&n);
	a=0;
	nr=0;
	for (i=1;i<=n;i++)
	{
		fscanf(in,"%lld",&x);
		if (x>a)
		{
			nr+=x-a;
		}
		a=x;
	}
	fprintf(out,"%lld\n",nr);
	fclose(in);
	fclose(out);
	return 0;
}