Problem:
Score : 600 points

Problem Statement

Given is a positive integer N.

We will choose an integer K between 2 and N (inclusive), then we will repeat the operation below until N becomes less than K.

Operation: if K divides N, replace N with N/K; otherwise, replace N with N-K.

In how many choices of K will N become 1 in the end?

Constraints

2 \leq N \leq 10^{12}

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of choices of K in which N becomes 1 in the end.

Sample Input 1

6

Sample Output 1

3

There are three choices of K in which N becomes 1 in the end: 2, 5, and 6.

In each of these choices, N will change as follows:

When K=2: 6 \to 3 \to 1

When K=5: 6 \to 1

When K=6: 6 \to 1

Sample Input 2

3141

Sample Output 2

13

Sample Input 3

314159265358

Sample Output 3

9

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#define rep(a,n) for (ll a = 0; a < (n); ++a)
#define _GLIBCXX_DEBUG
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef vector<vector<ll> > Graph;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
const ll INF = 1e18;

/*  divisor(n)
    入力：整数 n
    出力：nのすべての約数
    計算量：O(√n)
*/
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}

int main(){
    ll n;
    cin >> n;
    ll ans = 0;
    auto f = divisor(n-1);
    set<ll>st;
    rep(i,f.size()){
        st.insert(f[i]);
    }
    ans += f.size();
    ans--;
    auto s = divisor(n);
    rep(i,s.size()){
        if(s[i]-1==0||s[i]-1==1)continue;
        if(st.count(s[i]-1)==0){
            ans++;
        }
    }
    cout << ans+1 << endl;
}