Задача про функцию

#undef NDEBUG
#ifdef _DEBUG
#define _GLIBCXX_DEBUG
#endif
 
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <list>
#include <vector>
#include <string>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cassert>
 
using namespace std;
 
#define forn(i, n) for(int i = 0; i < (int)(n); i++)
#define forn1(i, n) for(int i = 1; i <= (int)(n); i++)
#define all(a) (a).begin(), (a).end()
#define sz(a) (int)((a).size())
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define y1 __y1
#define endl '\n'
#define sqr(x) (x) * (x)
 
typedef long long li;
typedef long double ld;
typedef pair<ld, ld> pt;
 
const int INF = (int)(1e9);
const li INF64 = (li)(INF) * (li)(INF);
const ld eps = 1e-9;
const ld pi = ld(3.1415926535897932384626433832795);
 
bool in(int i, int j, int n, int m)
{
    return i >= 1 && i <= n && j >= 1 && j <= m;
}
 
inline int myrand()
{
    return rand() ^ (rand() << 15);
}
 
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
 
const int dxh[] = {-2, -1, 1, 2, 2, 1, -1, -2};
const int dyh[] = {1, 2, 2, 1, -1, -2, -2, -1};
 
const int N = 6;
 
map<li, li> dp;
set<li> states;
li n;
 
const li MOD = (1LL << 32);
 
li f(li n)
{
    states.insert(n);
    if(n <= 2)
        return 1;
    if(dp.count(n) > 0)
        return dp[n];
 
    if(n & 1LL)
        dp[n] = f(6 * n / 7) + f(2 * n / 3);
    else
        dp[n] = f(n - 1) + f(n - 3);
 
    while(dp[n] >= MOD)
        dp[n] -= MOD;
    return dp[n];
}
 
int main(){
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
 
    cout << setprecision(15) << fixed;
    cerr << setprecision(10) << fixed;
 
    srand(int(time(NULL)));
 
    cin >> n;
    cout << f(n) << endl;
    cerr << sz(states) << endl;
 
    cerr << "TIME == " << clock() << " ms" << endl;
    return 0;
}

states.insert(n); //она в начале функции