1076B - Divisor Subtraction - CodeForces Solution

#include<bits/stdc++.h>
#include<math.h>
using namespace std;
int main()
{
    //long long n,d,ans=1,i;

    long long n,i,r=0,l,j ;

    cin>>n;
    for(i=2;i<=sqrt(n);i++)
    {
        if(n%i==0){ r=i;
            break;}
    }
    if(r==0)cout<<"1\n";
    else
        cout<<(n-r)/2 +1<<endl;
}