Viết chương trình tìm số nguyên tố lớn nhất không vượt quá n (0 < n 10^7)

$\color{#1fdb91}{\texttt{C}}\color{#0aaec9}{\texttt{+}}\color{#e9418e}{\texttt{+}}$

#include <iostream>

using namespace std;

bool check(int x) {
    if (x < 2) return false;
    for (int i=2; i*i<=x; ++i) if (x % i == 0) return false;
    return true;
}

int main() {
    
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    
    int n;
    for (cin >> n; n; --n) if(check(n)) return cout << n, 0;
    cout << -1;
    
}

$\\$
\begin{array}{c|c|c}\color{#ffd710}{\texttt{\{}} \color{#8655d6}{\texttt{\{}}\ \ \color{#8cdcda}{\text{Daoanhviet96}}\ \ \color{#8655d6}{\texttt{\}}} \color{#ffd710}{\texttt{\}}}\end{array}