p5019
//贪心 p5019

在这里插入代码片
 //差分
 #include<iostream>
using namespace std;
long long n,d[100005],ans,cf[100005]={0},sum1,sum2;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)  cin>>d[i];
	for(int i=1;i<=n;i++)
	{
		cf[i]=d[i]-d[i-1];
		if(cf[i]<0)  sum1-=cf[i];
		if(cf[i]>0)  sum2+=cf[i];
	} 
	cout<<max(sum1,sum2)<<endl;
   return 0;
} 
//分治 
#include<iostream>
#include<cstdio>
using namespace std;

int a[10001],minn=0x7fffffff,n,des;
unsigned long long int sum; 

void operate(int head,int tail)
{
	minn=0x7fffffff;
	for(int i=head;i<=tail;++i)
	{
		if(a[i]<minn)
		{
			minn=a[i];
			des=i;
		}
	}
	for(int i=head;i<=tail;++i)
	{
		a[i]-=minn;
	}
	sum+=minn;
	return;
}

void search(int head,int tail)
{
	if(tail<head)  return;
	operate(head,tail);
	search(des+1,tail);
	search(head,des-1);
	return;
}

int main()
{
	cin>>n;
	for(int i=1;i<=n;++i)
	{
		cin>>a[i];
		if(a[i]<minn)
		{
			minn=a[i];
		}
	}
    search(1,n);
    cout<<sum;
    return 0;
    }
	// 贪心
#include<bits/stdc++.h>
using namespace std;
int n,a[100005];
long long ans=0;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)     cin>>a[i];
	for(int i=2;i<=n;i++)     if(a[i]>a[i-1]) ans+=a[i]-a[i-1];
	cout<<ans+a[1];
	return 0;
}