#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, ll> pil;
typedef pair<ll, int> pli;
typedef pair<double, double> pdd;
#define SQ(i) ((i)*(i))
#define MEM(a, b) memset(a, (b), sizeof(a))
#define SZ(i) static_cast<int>(i.size())
#define FOR(i, j, k, in) for (int i=j; i < (k) ; i+=in)
#define RFOR(i, j, k, in) for (int i=j; i >= (k) ; i-=in)
#define REP(i, j) FOR(i, 0, j, 1)
#define REP1(i, j) FOR(i, 1, j+1, 1)
#define RREP(i, j) RFOR(i, j, 0, 1)
#define ALL(_a) _a.begin(), _a.end()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define X first
#define Y second
template<typename T, typename S>
istream &operator >> (istream &is, pair<T, S> &p) {
return is >> p.X >> p.Y;
}
#ifdef tmd
#define TIME(i) Timer i(#i)
#define debug(...) do {\
fprintf(stderr, "%s - %d (%s) = ", __PRETTY_FUNCTION__, __LINE__, #__VA_ARGS__);\
_do(__VA_ARGS__);\
}while(0)
template<typename T> void _do(T &&_x) {cerr<<_x<<endl;}
template<typename T,typename ...S> void _do(T &&_x, S &&..._t) {cerr <<_x <<" ,"; _do(_t...);}
template<typename _a,typename _b> ostream& operator << (ostream &_s, const pair<_a, _b> &_p) {return _s << "(" << _p.X << "," << _p.Y << ")";}
template<typename It> ostream& _OUTC(ostream &_s, It _ita, It _itb)
{
_s << "{";
for (It _it=_ita; _it != _itb; _it++) {
_s <<(_it == _ita?"":",")<< *_it;
}
_s << "}";
return _s;
}
template<typename _a> ostream &operator << (ostream &_s, const vector<_a> &_c) {return _OUTC(_s,ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const array<_a,2> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const array<_a,3> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const array<_a,4> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const array<_a,5> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const set<_a> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s, const deque<_a> &_c) {return _OUTC(_s, ALL(_c));}
template<typename _a,typename _b> ostream &operator << (ostream &_s, const map<_a,_b> &_c) {return _OUTC(_s,ALL(_c));}
template<typename _t> void pary(_t _a,_t _b){_OUTC(cerr,_a,_b);cerr<<endl;}
#define IOS()
class Timer {
private:
string scope_name;
chrono::high_resolution_clock::time_point start_time;
public:
Timer (string name) : scope_name(name) {
start_time = chrono::high_resolution_clock::now();
}
~Timer () {
auto stop_time = chrono::high_resolution_clock::now();
auto length = chrono::duration_cast<chrono::microseconds>(stop_time - start_time).count();
double mlength = double(length) * 0.001;
debug(scope_name, mlength);
}
};
#else
#define TIME(i)
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0)
#endif
#include "sorting.h"
int n;
vector<int> org, fnl, pos;
vector<pii> opr, res;
void change (int pa, int pb) {
swap(fnl[pa], fnl[pb]);
swap(pos[fnl[pa]], pos[fnl[pb]]);
}
bool solve (int cnt) {
fnl = org;
for (int i=0; i<cnt; i++) {
swap(fnl[opr[i].X], fnl[opr[i].Y]);
}
debug(cnt, fnl);
pos.resize(n);
for (int i=0; i<n; i++) {
pos[fnl[i]] = i;
}
vector<pii> swp;
for (int i=0; i<n; i++) {
if (fnl[i] != i) {
swp.eb(i, fnl[i]);
int ot = fnl[i];
swap(fnl[pos[i]], fnl[i]);
pos[ot] = pos[i];
pos[i] = i;
}
}
debug(swp);
fnl = org;
for (int i=0; i<n; i++) {
pos[fnl[i]] = i;
}
if (swp.size() > cnt) return false;
res.clear();
for (int i=0; i<cnt; i++) {
change(opr[i].X, opr[i].Y);
int pa = 0, pb = 0;
if (i < SZ(swp)) {
pa = pos[swp[i].X];
pb = pos[swp[i].Y];
}
change(pa, pb);
res.eb(pa, pb);
}
return true;
}
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
n = N;
for (int i=0; i<N; i++) {
org.eb(S[i]);
}
for (int i=0; i<M; i++) {
opr.eb(X[i], Y[i]);
}
int L = -1, R = M;
while (L < R - 1) {
int M = (L + R) >> 1;
if (solve(M)) R = M;
else L = M;
}
solve(R);
debug(R, res.size());
assert(res.size() == R);
for (int i=0; i<R; i++) {
tie(P[i], Q[i]) = res[i];
}
debug(R);
return R;
}
