#include <cstdio>
#include <algorithm>
#define INF 2140000000
#define MaxN 1030
using namespace std;

int act=0,prv=0,N;
long long sol;
int main()
{
    freopen("operatii.in","r",stdin);
    freopen("operatii.out","w",stdout);
	
	scanf("%d",&N);
	for(int i=1;i<=N;i++)
	{
		prv=act;
		scanf("%d",&act);
		sol+=max(0,act-prv);
	}
	printf("%d",sol);
	return 0;
}