#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vi vector<int>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vll vector<ll>
#define FOR(i,n) for(int i=0;i<n;i++)
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
#define f first
#define s second

const int MOD = (int)1e9+7;

int main()
{
    ll x;
    cin>>x;
    if(x<=3){
        cout<<1<<endl;
        return 0;
    }
    ll d = (x+1)/2;
    ll dist;
    if(d%2==1){
        dist = x-1;
    }
    else{
        dist = x-3;
    }
    int bits =0;
    FOR(i,61){
        if(dist&(1LL<<i)) bits++;
    }
    if(bits!=1) cout<<"impossible\n";
    else if(d%2==1) cout<<1<<endl;
    else cout<<3<<endl;
    
    return 0;
}