DSU

ll high[N];
ll p[N];       // set p of i equal to i initially
ll find(ll x)
{
    if(p[x]!=x)
        p[x]=find(p[x]);
    return p[x];
}
void merge(ll x,ll y)
{
    ll Px,Py;
    Px=find(x);
    Py=find(y);
    if(high[Px]>high[Py])
        p[Py]=Px;
    else
        p[Px]=Py;
    if(high[Px]==high[Py])
        high[Py]++;
}