#include<iostream>
#include<cstdio>
#define mylittlesister
#define maxn 100002
using namespace std;
int n,a[maxn],ans=0;
//int n,a[maxn][21][2],b[maxn][21],l[2],r;
int main()
{
	freopen("BlockNOIP2013.in","r",stdin);
	freopen("BlockNOIP2013.out","w",stdout);
	scanf("%d",&n);
/*                   ST表版 不完全版（少了个查询函数） 
	for(int i=1;i<=n;i++)
	{
	  scanf("%d",&a[i][0][0]);
	  b[i][0]=a[i][0][0];
	  a[i][0][1]=i;
	}
	for(int j=1;(1<<j)<=n;j++)
	  for(int i=1;i+(1<<j)-1<=n;i++)
	  {
	  	if(a[i][j-1][0]<=a[i+(1<<(j-1))][j-1][0])
		{
		  a[i][j][0]=a[i][j-1][0];
		  a[i][j][1]=i;
		}
		else
		{
		  a[i][j][0]=a[i+(1<<(j-1))][j-1][0];
		  a[i][j][1]=i+(1<<(j-1));
		}
		b[i][j]=max(b[i][j-1],b[i+(1<<(j-1))][j-1]);
	  }
	l[0]=0;
	for(int i=1;i<=n+1;i++)
	{
	  if(a[i][0][0]==0)l[r=!r]=i;
	  
	}
*/    //写完ST表才想到正解。。。 
	for(int i=1;i<=n;i++)
	{
	  scanf("%d",&a[i]);
	  if(a[i]>a[i-1])ans+=(a[i]-a[i-1]);
	}
	printf("%d",ans);
	return 0;
}