D.cpp

#include<bits/stdc++.h>
#define vi vector<int>
#define mp map<int,int>
#define ump unordered_map <int,int>
#define ll long long int
#define pb push_back
#define mod 1000000007
#define int long long
#define  loop(i,x,n) for(int i=x;i<n;i++)
#define rloop(i,n) for(int i=n-1;i>=0;i--)
using namespace std;
/*************************************************************************************************/
bool isPrime(int n)
{
    for(int i=2;i*i<=n;i++)
    {
        if(n%i==0)
        return false;
    }
    return true;
}                                                                           
signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin>>n;
    int ans=0;
    if(isPrime(n))
    ans=1;
    else if(n%2==0)
    ans=2;
    else
    {
        if(isPrime(n-2))
        ans=2;
        else 
        ans=3;
    }
    cout<<ans;
    return 0;
}