#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
typedef char cr;
ll n,s,a[150100];
bool p=true;
int main()
{
	cin>>n;
	for(int i=1;i<=n;i++) cin>>a[i];
	for(int i=1;i<=n;i++)
	{
		if(a[i]>a[i-1]&&p==1)s+=a[i],p=0;
		if(a[i]<a[i+1]&&p==0)s-=a[i],p=1;
	}
	cout<<s;
}

#include<bits/stdc++.h>
using namespace std;
int p,a,x,y,ma;
int read(){
	int x=0;char ch=getchar();
	while(ch<'0'||ch>'9') ch=getchar();
	while(ch>='0'&&ch<='9'){
		x=x*10+ch-48;
		ch=getchar();
	}
	return x;
}
int main(){
	p=read();
	for(int i=1;i<=p;i++){
		a=read();
		if(y+a>x) x=y+a;
		if(x-a>y) y=x-a;
	}
	if(x>y) printf("%d",x);
	else printf("%d",y); 
	return 0;
}