#include "sorting.h"
#include <bits/stdc++.h>
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) (int)a.size()
#define x first
#define y second
#define debug(...) cout << "[" << #__VA_ARGS__ << ": " << __VA_ARGS__ << "]\n"
#define rd() abs((int)rng())
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int>pii;
const int maxn = 2e5 + 100;
const int mod = 1e9 + 7;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
int findSwapPairs(int n, int arr[], int m, int X[], int Y[], int P[], int Q[])
{
auto chk = [&](int val, bool f = false) -> bool
{
vector<int>finalpos(n, 0);
for(int i = 0; i < n; i++)
finalpos[i] = i;
for(int i = val - 1; i >= 0; i--)
swap(finalpos[X[i]], finalpos[Y[i]]);
vector<int>where(n), wheref(n), v(n);
for(int i = 0; i < n; i++)
{
wheref[finalpos[i]] = i;
v[i] = arr[i];
where[v[i]] = i;
}
int sw = 0;
swap(finalpos[X[sw]], finalpos[Y[sw]]);
swap(wheref[finalpos[X[sw]]], wheref[finalpos[Y[sw]]]);
swap(v[X[sw]], v[Y[sw]]);
swap(where[v[X[sw]]], where[v[Y[sw]]]);
for(int i = 0; i < n; i++)
{
if(finalpos[where[i]] != i)
{
if(sw >= val)
return false;
int pos = wheref[i];
P[sw] = where[i], Q[sw] = pos;
swap(v[pos], v[where[i]]);
swap(where[v[pos]], where[v[where[i]]]);
assert(finalpos[where[i]] == i);
++sw;
if(sw < val)
{
swap(finalpos[X[sw]], finalpos[Y[sw]]);
swap(wheref[finalpos[X[sw]]], wheref[finalpos[Y[sw]]]);
swap(v[X[sw]], v[Y[sw]]);
swap(where[v[X[sw]]], where[v[Y[sw]]]);
}
}
}
while(sw < m)
{
P[sw] = Q[sw] = 0;
++sw;
}
return true;
};
if(is_sorted(arr, arr + n))
return 0;
int l = 1, r = m;
while(l < r)
{
int mid = (l + r) / 2;
if(chk(mid))
r = mid;
else
l = mid + 1;
}
chk(l);
return l;
}
