Common Smallest Prime Divisor - HackerEarth

#include<bits/stdc++.h>
using namespace std;

int main()
{
    
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
 
    long long a,b;
    
    cin >> a >> b;
    long long aaa,bbb;
    aaa=a;
    bbb=b;
    vector<long long>aa,bb;
    for(int i=2;i<=sqrt(aaa);i++)
    {
      if(a%i==0)
      {
         aa.push_back(i);
         while(a%i==0)
         a/=i;
      }
    }
    if(a>1)
    aa.push_back(a);
    for(int i=2;i<=sqrt(bbb);i++)
    {
      if(b%i==0)
      {
         bb.push_back(i);
         while(b%i==0)
         b/=i;
      }
    }
    if(b>1)
    bb.push_back(b);

    for(int i=0;i<aa.size();i++)
    {
       if(binary_search(bb.begin(),bb.end(),aa[i]))
       {
          cout<<aa[i];
          return 0;
       }
    }
      cout<<-1;
    return 0;
}