Default Template

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define mp make_pair
#define pb push_back
#define ALL(A) A.begin(),A.end()
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(a);i>=(b);i--)
#define SZ(A) A.size()

typedef vector<int> VI;
typedef vector<pair<int,int> > VII;
typedef pair<int,int> pii;
typedef pair<int,pair<int,int> > pip;
typedef pair<pair<int,int>,pair<int,int> > ppp;
typedef pair<pair<int,int>,int> ppi;

const long double PI=acos(-1);
const int INF=(int)1e18;
const int MOD=(int)1e9+7;

int gcd(int a,int b)
{
    if(b) return gcd(b,a%b);
    return a;
}

void rec();

bool isPalindrom(int i,int j)
{
    for(;i<j;i++,j--)
    {
        if(v[i]!=v[j])
            return false;
    }
    return true;
}

signed main()
{
    ios::sync_with_stdio(0); cin.tie(nullptr); cout.tie(nullptr);
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);

    return 0;
}