#include "sorting.h"
#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

#define ll long long
#define ld long double
#define endl '\n'
#define st first
#define nd second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
int inf=2000000007;
ll infl=1000000000000000007;
ll mod=1000000007;



int findSwapPairs(int n, int S[], int m, int X[], int Y[], int P[], int Q[])
{
	bool ok=1;
	FOR(i,0,n-1) ok&=(S[i]==i);
	if(ok) return 0;
    int l=1,r=m,sr,ans=m;
    while(l<=r)
    {
		vector<int>ord(n),p(n),pos(n),odw(n,0);
		FOR(i,0,n-1) 
		{
			ord[i]=i;
			pos[i]=i;
		}
		sr=(l+r)/2;
		FOR(i,0,sr-1) swap(pos[X[i]],pos[Y[i]]); 
		FOR(i,0,n-1) ord[pos[i]]=i;
		FOR(i,0,n-1) p[S[i]]=ord[i];
		FOR(i,0,n-1) debug(p[i]);
		FOR(i,0,n-1) debug(ord[i]);
		vector<pair<int,int>>res;
		FOR(i,0,n-1)
		{
			if(odw[i]) continue;
			int x=i;
			vector<int>V;
			while(!odw[x])
			{
				if(x!=i) V.pb(x);
				debug(i,x);
				odw[x]=1;
				x=p[x];
			}
			for(auto j:V) res.pb({i,j});
		}
		if(sz(res)<=sr)
		{
			ans=sr;
			r=sr-1;
			FOR(i,0,sr-1)
			{
				P[i]=res[i].st;
				Q[i]=res[i].nd;
			}
		}
		else l=sr+1;
	}
	debug(ans);
	vector<int>pos(n);
	FOR(i,0,n-1) pos[S[i]]=i;
	FOR(i,0,ans-1) 
	{
		swap(pos[S[X[i]]],pos[S[Y[i]]]);
		swap(S[X[i]],S[Y[i]]);
		P[i]=pos[P[i]];
		Q[i]=pos[Q[i]];
		swap(pos[S[P[i]]],pos[S[Q[i]]]);
		swap(S[P[i]],S[Q[i]]);
	}
	FOR(i,0,n-1) debug(S[i]);
	FOR(i,0,ans-1) debug(P[i],Q[i]);
	return ans;
}