#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;
const int maxn=1e6+7;
bool not_pr[maxn];int pr[maxn],sz,fac[maxn],fz,P;
typedef long long ll;
void Sieve(){
    int i,j;
    for(i=2;i<maxn;++i){
        if(!not_pr[i]) pr[sz++]=i;
        for(j=0;j<sz&&i*pr[j]<maxn;++j){
            not_pr[i*pr[j]]=1;
            if(i%pr[j]==0) break;
        }
    }
}
void factor(int p){
    fz=0;int tmp=p-1,i;
    for(i=0;i<sz;++i){
        if(tmp==1) break;
        if(tmp%pr[i]==0){
            for(tmp/=pr[i];tmp%pr[i]==0;tmp/=pr[i]);    //这里是分号
            fac[fz++]=pr[i];
        }
    }
    if(tmp!=1) fac[fz++]=tmp;    
}
ll mod_pow(ll a,ll b,ll p){
    if(b==0) return 1;
    ll ans=1;
    while(b){
        if(b&1) ans=(ans*a)%p;
        a=(a*a)%p;
        b>>=1;
    }
    return ans;
}
bool judge(int x){
    int i;
    for(i=0;i<fz;++i){
        if(mod_pow(x,(P-1)/fac[i],P)==1) return false;
    }
    return true;
}
int main(){
    Sieve();
    while(~scanf("%d",&P)){
        factor(P);
        for(int i=2;;++i) if(judge(i)) {printf("%d\n",i);break;}
    }
    return 0;
}