HackerEarth Killjee and cities problem solution

#include<bits/stdc++.h>
using namespace std;
int rnk[1000005],par[1000005];
int findparent(int val)
{
    if(par[val]==val)return val;
    return par[val]=findparent(par[val]);
}
void makeunion(int a,int b)
{
    int para=findparent(a);
    int parb=findparent(b);
    if(para==parb)return;
    else
    {
        if(rnk[para]<rnk[parb])
            par[parb]=para;
        else if(rnk[parb]<rnk[para])
            par[para]=parb;
        else
        {
            par[parb]=para;
            rnk[para]++;
        }
    }
}
int main()
{
    int n,m,q,s;
    cin>>n>>m>>s;
    assert(n>=1 && n<=1e6);
    assert(m>=0 && m<=1e6);
    assert(s==2);
    for(int i=1;i<=1000000;i++)par[i]=i;
    for(int i=1;i<=m;i++)
    {
        int x,y;
        cin>>x>>y;
        assert(x>=1 && x<=n);
        assert(y>=1 && y<=n);
        assert(x!=y);
        makeunion(x,y);
    }
    int com=0;
    for(int i=1;i<=n;i++)if(par[i]==i)com++;
    cin>>q>>s;
    assert(q>=1 && q<=1e6);
    assert(s==2);
    while(q--)
    {
        int x,y;
        cin>>x>>y;
        assert(x>=1 && x<=n);
        assert(y>=1 && y<=n);
        assert(x!=y);
        if(findparent(x)!=findparent(y)){makeunion(x,y);com--;}
        cout<<com-1<<" ";
    }
    return 0;
}