#include "sorting.h"
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i = (a); i <= (b); i++)
#define debug(a) cout << #a << " = " << a << endl
int sum,largo,act,cont;
int seg,n,m,w,pas;
int s[200001],x[600001],y[600001],doble[200001],visitados[200001];
bool checa(int pos) {
rep(i,0,n-1) visitados[i] = 0;
rep(i,0,n-1) doble[i] = s[i];
rep(i,0,pos) swap(doble[x[i]],doble[y[i]]);
sum = 0;
rep(i,0,n-1) {
if (visitados[i] == 0) {
act = doble[i];
largo = 0;
visitados[i] = 1;
while (act != i) {
largo++;
visitados[act] = 1;
act = doble[act];
}
sum += largo;
}
}
if (sum <= (pos+1)) return true;
else return false;
}
void binaria(int ini, int fin) {
int mitad;
if (ini <= fin) {
mitad = (ini+fin)/2;
if (checa(mitad)) {
seg = mitad;
binaria(ini,mitad-1);
}
else binaria(mitad+1 ,fin);
}
}
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
n = N;
m = M;
rep(i,0,N) s[i] = S[i];
rep(i,0,M) x[i] = X[i];
rep(i,0,M) y[i] = Y[i];
binaria(0,M-1);
rep(i,0,n-1) visitados[i] = 0;
rep(i,0,n-1) doble[i] = s[i];
rep(i,0,seg) swap(doble[x[i]],doble[y[i]]);
cont = 0;
rep(i,0,n-1) {
if (visitados[i] == 0) {
act = doble[i];
pas = i;
visitados[i] = 1;
while (act != i) {
P[cont] = pas;
Q[cont] = act;
cont++;
visitados[act] = 1;
pas = act;
act = doble[act];
}
}
}
cerr << seg;
return (seg+1);
}
