#include<bits/stdc++.h>
using namespace std;
int n;
int a[200005],b[200005];
vector<pair<int,int> >q;
void merge_sort(int l,int r){
	//cout << l << " " << r << endl;
	if(l >= r)return;
	if(l+1 == r){
		if(b[l+1] == 0 and b[l] == 1)swap(a[l],a[r]),swap(b[l],b[r]),q.push_back({l,l+1});
		return;
	}int mid = l+r>>1;
	merge_sort(l,mid),merge_sort(mid+1,r);
	int pos1,pos3 = r+1;
	//cout << l << "  " << r << endl;
//	for(int i = l;i<=mid;i++)cout << b[i] << " ";cout << endl;
//	for(int i = mid+1;i<=r;i++)cout << b[i] << " ";cout << endl;
	if(b[mid] == 0 or b[mid+1] == 1)return;
	for(int i = l;i<=mid;i++){
		if(b[i] == 1){
			pos1 = i;break;
		}
	}for(int i = mid+1;i<=r;i++){
		if(b[i] == 1){
			pos3 = i;break;
		}
	}pos3--;
	q.push_back({pos1,pos3});
//	cout << pos1 <<"  " << pos3 << endl;
	reverse(a+pos1,a+pos3+1),reverse(b+pos1,b+pos3+1);
}
void solve(int l,int r,int d){
	if(d == -1)return;
	if(l>=r)return;
//	cout << l <<" " << r << endl;
	for(int i = l;i<=r;i++)b[i] = a[i]>>d&1;
	merge_sort(l,r);
//	for(int i = l;i<=r;i++)cout << b[i] <<" ";cout << endl;
	int pos =r+1;
	for(int i = l;i<=r;i++){
		if(b[i] == 1){
			pos = i;break;
		}
	}solve(l,pos-1,d-1),solve(pos,r,d-1);
}
signed main(){
	int mx =0;srand(time(0));
	cin >> n;
	for(int i = 1;i<=n;i++)cin >> a[i];
	//n = 32000;
	//for(int i = 1;i<=n;i++)a[i] = rand()%32000;
	for(int i = 1;i<=n;i++)mx = max(mx,a[i]);
	int pro = 1,cnt =-1;
	while(pro<=mx)pro*=2,cnt++;pro/=2;
	solve(1,n,cnt);
	cout << q.size() << '\n';
	for(int i = 0;i<q.size();i++)cout << q[i].first <<" " << q[i].second << '\n';
	int sum = 0;
	for(int i =0;i<q.size();i++)sum+=q[i].second-q[i].first+1;
//	cout << sum << endl;
//	for(int i = 1;i<=n;i++)cout << a[i] << " ";cout << endl;
	return 0;
}