#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<vector>
#define ll long long
#define pll pair<ll,ll>
using namespace std;
const int MN=5e5+5;
ll n,a[MN];
vector<pll> ans;
ll max(ll x, ll y){if(x<y)return y;return x;}
void write(ll n){if(n<0){putchar('-');write(-n);return;}if(n>9)write(n/10);putchar(n%10+'0');}
ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return x*f;}
void work(ll l, ll r){if(l==r) return;ans.push_back({l,r});reverse(a+l,a+1+r);}
ll merge_sort(ll l, ll r, ll k){
    if(l==r) return (a[l]>>k)&1;
    ll mid=l+r>>1;ll num1=merge_sort(l,mid,k),num2=merge_sort(mid+1,r,k);
    if(num1) work(mid-num1+1,r-num2);
    return num1+num2;
}
void solve(ll l, ll r, ll k){
    if(k<0||l>r) return;
    ll maxn=0;for(int i=1; i<=n; i++) maxn=max(maxn,a[i]);
    ll num=merge_sort(l,r,k);
    solve(l,r-num,k-1);solve(r-num+1,r,k-1);
}
int main(){
    // freopen("1.in","r",stdin);
    // freopen("1.out","w",stdout);
    n=read();ll maxn=0;
    for(int i=1; i<=n; i++) a[i]=read(),maxn=max(maxn,a[i]);
    if(maxn) solve(1,n,__lg(maxn));
    write(ans.size());putchar('\n');
    for(int i=0; i<ans.size(); i++) write(ans[i].first),putchar(' '),write(ans[i].second),putchar('\n');
    return 0;
}