#include "sorting.h"
#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define per(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
typedef long long ll;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
const ll INF = 1'000'000'007;
bool isSorted(int N, int S[]) {
rep(i,0,N) if(S[i]!=i) return false;
return true;
}
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
P[0] = 0;
Q[0] = 0;
vll s;
ll n=N;
ll lo=0,hi=M;
while(lo!=hi) {
//cout<<"lo = "<<lo<<" hi = "<<hi<<endl;
ll mid=(lo+hi)/2;
rep(i,0,n) s.pb(S[i]);
rep(i,0,mid) swap(s[X[i]],s[Y[i]]);
vpll item_swaps;
rep(i,0,n) while(s[i]!=i) {
//cout<<"i = "<<i<<" s[i] = "<<s[i]<<" s[s[i]] = "<<s[s[i]]<<endl;
item_swaps.emplace_back(s[i],s[s[i]]);
swap(s[i],s[s[i]]);
}
//cout<<sz(item_swaps)<<endl;
if(sz(item_swaps)<=mid) hi=mid;
else lo=mid+1;
s.clear();
}
//cout<<"lo = "<<lo<<endl;
rep(i,0,n) s.pb(S[i]);
rep(i,0,lo) swap(s[X[i]],s[Y[i]]);
//cout<<"seq"<<endl;
//rep(i,0,n) cout<<s[i]<<' ';
//cout<<endl;
vpll item_swaps;
rep(i,0,n) while(s[i]!=i) {
item_swaps.emplace_back(s[i],s[s[i]]);
swap(s[i],s[s[i]]);
}
rep(i,sz(item_swaps),lo) item_swaps.emplace_back(0,0);
//cout<<"swaps"<<endl;
//rep(i,0,sz(item_swaps)) cout<<item_swaps[i].first<<' '<<item_swaps[i].second<<endl;
//cout<<endl;
vll indexes(n);
rep(i,0,n) indexes[S[i]]=i;
rep(i,0,sz(item_swaps)) {
ll a=S[X[i]],b=S[Y[i]];
swap(S[X[i]],S[Y[i]]);
swap(indexes[a],indexes[b]);
tie(a,b)=item_swaps[i];
P[i]=indexes[a];
Q[i]=indexes[b];
swap(S[indexes[a]],S[indexes[b]]);
swap(indexes[a],indexes[b]);
}
return lo;
}
/*
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "sorting.h"
static char _buffer[1024];
static int _currentChar = 0;
static int _charsNumber = 0;
static FILE *_inputFile, *_outputFile;
static inline int _read() {
if (_charsNumber < 0) {
exit(1);
}
if (!_charsNumber || _currentChar == _charsNumber) {
_charsNumber = (int)fread(_buffer, sizeof(_buffer[0]), sizeof(_buffer), _inputFile);
_currentChar = 0;
}
if (_charsNumber <= 0) {
return -1;
}
return _buffer[_currentChar++];
}
static inline int _readInt() {
int c, x, s;
c = _read();
while (c <= 32) c = _read();
x = 0;
s = 1;
if (c == '-') {
s = -1;
c = _read();
}
while (c > 32) {
x *= 10;
x += c - '0';
c = _read();
}
if (s < 0) x = -x;
return x;
}
int main()
{
_inputFile = fopen("sorting.in", "rb");
int N, M;
N = _readInt();
int *S = (int*)malloc(sizeof(int) * (unsigned int)N);
for (int i = 0; i < N; ++i)
S[i] = _readInt();
M = _readInt();
int *X = (int*)malloc(sizeof(int) * (unsigned int)M), *Y = (int*)malloc(sizeof(int) * (unsigned int)M);
for (int i = 0; i < M; ++i) {
X[i] = _readInt();
Y[i] = _readInt();
}
int *P = (int*)malloc(sizeof(int) * (unsigned int)M), *Q = (int*)malloc(sizeof(int) * (unsigned int)M);
int ans = findSwapPairs(N, S, M, X, Y, P, Q);
printf("%d\n", ans);
for (int i = 0; i < ans; ++i)
printf("%d %d\n", P[i], Q[i]);
_Exit(0);
return 0;
}
*/
