#include "bits/stdc++.h"
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pii pair<int,int>
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define pb push_back
#define sz(x) (int)(x).size()
#define rsz resize
#define ass assign
#define F(i,l,r) for(int i=(l);i<(r);++i)
typedef long long ll;
typedef unsigned long long ull;
typedef long double lld;
//template<typename T> using pqg = priority_queue<T, vector<T>, greater<T>>;
#define each(a,x) for(auto a:x)
#define FOR(i,a) for(int i=0;i<(a);i++)
#define ROF(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define eb emplace_back
#define ft front()
#define V vector
#include "shoes.h"
ll count_swaps(V<int> s){
ll n=sz(s)/2;
return (n*(n-1))/2;
}
//*
//ll count_swaps(V<int> s){
// ll n=(ll)s.size()/2;
// ll res=0;
// FOR(i,n){
// ll id=-1;
// FOR(j,sz(s)){
// if(s[0]==-s[j]){
// id=j;
/// break;
// }
// }
//}
//}
