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#include <bits/stdc++.h>
#define FOR(i, a, b) for (long long i = (a); i <= (b); ++i)
#define ROF(i, a, b) for (long long i = (a); i >= (b); --i)
#define all(x) x.begin(),x.end()
#define CLR(i,a) memset(i,a,sizeof(i))
#define fi first
#define se second
#define pb push_back
#define SZ(a) ((int) a.size())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> pll;
typedef array<ll,3> arr;
typedef double DB;
typedef pair<DB,DB> pdd;
constexpr ll MAXN=static_cast<ll>(1e6)+10,INF=static_cast<ll>(5e18)+3;
ll N,M,T,A[MAXN];
inline void solve(){
cin>>N;
if(N==2){
cout<<1<<"\n";
return;
}
if(N%2==0){
cout<<2<<"\n";
}else{
bool isPrime=true;
for(int i=2;i<=floor(sqrt(N));++i){
if(N%i==0){
isPrime=false;
break;
}
}
if(isPrime){
cout<<1<<"\n";
return;
}
bool isPrime2=true;
for(int i=2;i<=floor(sqrt(N-2));++i){
if((N-2)%i==0){
isPrime2=false;
break;
}
}
if(isPrime2){
cout<<2<<"\n";
return;
}
cout<<3<<"\n";
return;
}
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
solve();
return 0;
}
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