#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp> 
#include <ext/pb_ds/detail/standard_policies.hpp>
using namespace __gnu_pbds;
using namespace std;
#define getbit(n, i) (((n) & (1LL << (i))) != 0) 
#define setbit0(n, i) ((n) & (~(1LL << (i)))) 
#define setbit1(n, i) ((n) | (1LL << (i))) 
#define togglebit(n, i) ((n) ^ (1LL << (i))) 
#define lastone(n) ((n) & (-(n))) 
char gap = 32;
#define int long long
#define ll long long 
#define lll __int128_t
#define pb push_back
#define pii pair<int,int>
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll hashPrime = 1610612741;

const int N = 1120;
int ara[N];
int sorted[N];
pii target[N];

vector<pii> res;

void solve(int n) {
    if (n == 1) return;
    for (int i=0; i<n; i++) if (ara[i] == sorted[n-1]) {
        if (i != n-1) {
            int cur = i;
            // take i to zero
            for (int pos = 0; pos <= 12; pos++) {
                if ((cur >> pos) & 1) {
                    res.pb({cur, cur ^ (1 << pos)});
                    swap(ara[cur], ara[cur ^ (1 << pos)]);
                    cur ^= (1 << pos);
                }
            }
            cur = 0;
            // take 0 to n-1
            for (int pos = 0; pos <= 12; pos++) {
                if (((n-1) >> pos) & 1) {
                    res.pb({cur, cur ^ (1 << pos)});
                    swap(ara[cur], ara[cur ^ (1 << pos)]);
                    cur ^= (1 << pos);
                }
            }
        }
        solve(n-1);
        return;
    }
}

void solve(){
    int n;
    cin >> n;
    n = 1<<n;
    for (int i=0; i<n; i++) cin >> ara[i];
    for (int i=0; i<n; i++) sorted[i] = ara[i];
    sort(sorted, sorted + n);

    solve(n);

    // for(int i=0;i<n;i++)    target[i] = {ara[i], i};
    // sort(target, target+n);
    // for(int i=0;i<n;i++)    cur[i] = target[i].second;
    
    // for (int i=n-1; i>=0; i--) {
    //     //if (ara[i] == target[i].first) continue;
    //     int pos = cur[i];
    //     int mul = 1;
    //     for(int b=0;b<=12;b++){
    //         if( mul & pos ){
    //             res.pb({pos, pos^mul});
    //             //cout<<pos<<" "<<(pos^mul)<<endl;
    //             swap(cur[pos], cur[pos^mul]);
                
    //             pos ^= mul;
    //         }
    //         mul = mul<<1;
    //     }
    //     pos = 0;
    //     mul = 1;
    //     for(int b=0;b<=12;b++){
    //         if( mul & i ){
    //             res.pb({pos, pos^mul});
    //            // cout<<pos<<" "<<(pos^mul)<<endl;
    //             swap(cur[pos], cur[pos^mul]);
    //             pos ^= mul;
    //         }
    //         mul <<= 1;
    //     }


    // }
    cout<<res.size()<<endl;
    for(auto p: res) cout << p.first << " " << p.second << endl;

}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
     solve();
    
    return 0;
}