#include <cstdio>

int main (void)
{
	std::freopen("operatii.in","r",stdin);
	std::freopen("operatii.out","w",stdout);
	unsigned int n;
	std::scanf("%u",&n);
	unsigned int result(0), previous(0), number, *number_ptr(&number);
	do
	{
		std::scanf("%u",number_ptr);
		if (number > previous)
			result += number - previous;
		previous = number;
		--n;
	}
	while (n);
	std::fclose(stdin);
	std::printf("%u\n",result);
	std::fclose(stdout);
	return 0;
}