ABC280D WA

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#define dbg(...) logger(#__VA_ARGS__, __VA_ARGS__)
template <typename... Args> void logger(string vars, Args &&... values)
{
    cerr << vars << " = ";
    string delim = "";
    (..., (cerr << delim << values, delim = ", "));
    cerr << endl;
}

template <class T> inline auto vv(int m) { return vector<vector<T>>(m, vector<T>(m)); }
template <class T> inline auto vv(int m, int n) { return vector<vector<T>>(m, vector<T>(n)); }
template <class T, T init> inline auto vv(int m) { return vector<vector<T>>(m, vector<T>(m, init)); }
template <class T, T init> inline auto vv(int m, int n) { return vector<vector<T>>(m, vector<T>(n, init)); }

template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;
using vi = vector<int>;
using ll = long long;
using pii = pair<int, int>;

const int MAXN = 1e6 + 27;
int not_prime[MAXN];
ll prime[MAXN], pcnt = 0;

void seive()
{
    for (int i = 2; i < MAXN; ++i) {
        if (!not_prime[i]) {
            prime[pcnt++] = i;
        }
        for (int j = 0; j < pcnt && prime[j] * i < MAXN; ++j) {
            not_prime[prime[j] * i] = 1;
            if ((i % prime[j]) == 0)
                break;
        }
    }
}

int main(int argc, char **argv)
{
    ll k;
    cin >> k;
    seive();
    // dbg("after seive");
    dbg(MAXN, prime[pcnt - 1]);

    map<ll, int> factor;
    for (int i = 0; i < pcnt; ++i) {
        while (k % prime[i] == 0) {
            k = k / prime[i];
            factor[prime[i]] += 1;
        }
    }
    if (k != 1)
        factor[k] += 1;
    ll max_val = 1;
    for (const auto &p : factor) {
        max_val = max(max_val, p.first * p.second);
    }
    cout << max_val << endl;
    return 0;
};