#include<bits/stdc++.h> using namespace std; int n,ans1; int a[200005]; int vis[200005]; struct wsw{ int b,d; }; wsw ans[200005]; int main(){ //freopen("sort.in","r",stdin); //freopen("sort.out","w",stdout); cin>>n; for(int i=1;i<=n;i++){ cin>>a[i]; vis[a[i]]=i; } for(int i=1;i<=n;i++){ if(a[i]!=i){ ans1++; ans[ans1].b=min(i,vis[i]); ans[ans1].d=max(i,vis[i]); swap(a[i],a[vis[i]]); vis[a[vis[i]]]=vis[i]; vis[i]=i; } } printf("%d\n",ans); for(int i=1;i<=ans1;i++){ printf("%d %d\n",ans[i].b,ans[i].d); } //fclose(stdin); //fclose(stdout); return 0; }