//Think simple yet elegant.
#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll  long long
#define all(v) v.begin(),v.end()
#define F first
#define S second
#define pb push_back
#define mp make_pair
#define pi pair<ll,ll>
#define REP(i,n) for(int i=0;i<n;i++)
#define deb(...) [](const auto&...x){ char c='='; cerr<<#__VA_ARGS__<<" "; ((cerr<<exchange(c,',')<<" "<<x),...); cerr<<"\n"; }(__VA_ARGS__);
const int N = 1e5+10;
vector<vector<int>> g(200010);
vector<bool> vis(200010,false);
set<int> h;

void dfs(int v){
	vis[v]=true;
	h.insert(v);
	for(int to : g[v]){
		if(!vis[to])
			dfs(to);
	}
}
void run_case(){
	int n,i;
	cin >> n;
	vector<int> a(n);
	for(i=0;i<n;i++)
		cin >> a[i];
	for(i=0;i<n/2;i++){
		if(a[i]!=a[n-1-i]){
			g[a[i]].pb(a[n-1-i]);
			g[a[n-1-i]].pb(a[i]);
		}
	}	
	int cnt = 0;
	for(i=1;i<=2e5;++i){
		if((int)g[i].size()==0)
			continue;
		if(!vis[i]){
			h.clear();
			dfs(i);
			cnt+=(int)h.size()-1;
		}
	}
	cout<<cnt;
}
 
int main(){
	fast;
	int t=1;
	while(t--){
		run_case();
	}
}

//Think simple yet elegant.
#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll  long long
#define all(v) v.begin(),v.end()
#define F first
#define S second
#define pb push_back
#define mp make_pair
#define pi pair<int,int>
#define REP(i,n) for(int i=0;i<n;i++)
#define deb(...) [](const auto&...x){ char c='='; cerr<<#__VA_ARGS__<<" "; ((cerr<<exchange(c,',')<<" "<<x),...); cerr<<"\n"; }(__VA_ARGS__);
const int mx = 1e6+10;
const int INF = 1e9;
vector<int> mu(mx+10);
#define N 1000010
 
ll lpf[N], mobius[N];
 
// Function to calculate least
// prime factor of each number
void least_prime_factor()
{
    for (ll i = 2; i < N; i++)
 
        // If it is a prime number
        if (!lpf[i])
 
            for (ll j = i; j < N; j += i)
 
                // For all multiples which are not
                // visited yet.
                if (!lpf[j])
                    lpf[j] = i;
}
 
// Function to find the value of Mobius function
// for all the numbers from 1 to n
void Mobius()
{
    for (ll i = 1; i < N; i++) {
 
        // If number is one
        if (i == 1)
            mobius[i] = 1;
        else {
 
            // If number has a squared prime factor
            if (lpf[i / lpf[i]] == lpf[i])
                mobius[i] = 0;
 
            // Multiply -1 with the previous number
            else
                mobius[i] = -1 * mobius[i / lpf[i]];
        }
    }
}
 
// Function to find the number of pairs
// such that gcd equals to 1
ll gcd_pairs(ll a[], ll n)
{
    // To store maximum number
    ll maxi = 0;
 
    // To store frequency of each number
    ll fre[N] = { 0 };
 
    // Find frequency and maximum number
    for (ll i = 0; i < n; i++) {
        fre[a[i]]++;
        maxi = max(a[i], maxi);
    }
 
    least_prime_factor();
    Mobius();
 
    // To store number of pairs with gcd equals to 1
    ll ans = 0;
 
    // Traverse through the all possible elements
    for (ll i = 1; i <= maxi; i++) {
        if (!mobius[i])
            continue;
 
        ll temp = 0;
        for (ll j = i; j <= maxi; j += i)
            temp += fre[j];
 
        ans += temp * (temp - 1) / 2 * mobius[i];
    }
 
    // Return the number of pairs
    return ans;
}
void mu_calc(){ 

	for (int i = 1; i <= mx; i++)
        mu[i] = 1;
    for (int i = 2; i*i <= mx; i++)
    {
        if (mu[i] == 1)
        {
            for (int j = i; j <= mx; j += i)
                mu[j] *= -i;
            for (int j = i * i; j <= mx; j += i * i)
                mu[j] = 0;
        }
    }
    for (int i = 2; i <= mx; i++)
    {
        if (mu[i] == i)
            mu[i] = 1;
        else if (mu[i] == -i)
            mu[i] = -1;
        else if (mu[i] < 0)
            mu[i] = 1;
        else if (mu[i] > 0)
            mu[i] = -1;
    }
}


void run_case(){
	ll l,r,d,j,i;
	cin >> l >> r;
	ll c1 = 0,c2 = 0,c3 = 0,a1=0;

	ll a[r-l+1];

	for(d=1;d<=r;++d){
		a1+=mu[d]*(r/d)*(r/d);
	}
	for(i=l;i<=r;i++)
		a[i-l] = i;
	

	c1 = 2LL*gcd_pairs(a,r-l+1);
//	cout<<c1<<" "<<a1<<endl;
	for(i=l;i<=r;++i){
		for(j=i;j<=r;j+=i)
			++c3;
	}
	c3*=2;
	c3-=(r-l+1);
	ll ans = (r-l+1)*(r-l+1) - c1 - c3;
	if(l==1){
		ans+=2*r - 2;
	}
	cout<<ans<<"\n";

}

int main(){
	fast;
	mu_calc();
	int t=1;
	while(t--){
		run_case();
	}
}