在学组合数4的时候不会算数基本定理，所以刷的题，跟学的知识点

#include <bits/stdc++.h>

using namespace std;

const int N = 1e6 + 10;

int primes[N], cnt;
bool st[N];

void get_primes(int n)
{
    for (int i = 2; i <= n; i ++ )
    {
        if (!st[i]) primes[cnt ++ ] = i;
        for (int j = 0;  primes[j] <= n / i; j ++ )
        {
            st[primes[j] * i] = true;
            if (i % primes[j] == 0) break;
        }
    }
}

int main()
{
    int n;
    cin >> n;

    get_primes(n);

    for (int i = 0; i < cnt ;i ++ )
    {
        int res = 0, t = n;
        while (t) res += (t / primes[i]), t /= primes[i];

        printf("%d %d\n", primes[i], res);
    }

    return 0;
}