<p>Given an integer n, return <em>the smallest <strong>prime palindrome</strong> greater than or equal to </em><code>n</code>.</p>

<p>An integer is <strong>prime</strong> if it has exactly two divisors: <code>1</code> and itself. Note that <code>1</code> is not a prime number.</p>

<ul>
	<li>For example, <code>2</code>, <code>3</code>, <code>5</code>, <code>7</code>, <code>11</code>, and <code>13</code> are all primes.</li>
</ul>

<p>An integer is a <strong>palindrome</strong> if it reads the same from left to right as it does from right to left.</p>

<ul>
	<li>For example, <code>101</code> and <code>12321</code> are palindromes.</li>
</ul>

<p>The test cases are generated so that the answer always exists and is in the range <code>[2, 2 * 10<sup>8</sup>]</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> n = 6
<strong>Output:</strong> 7
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> n = 8
<strong>Output:</strong> 11
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> n = 13
<strong>Output:</strong> 101
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 10<sup>8</sup></code></li>
</ul>

class Solution {
public:
    int primePalindrome(const int N) const {
        if (8 <= N && N <= 11) {
            return 11;
        }
        for (auto x = 1; x < 100000; ++x) {
            string s = to_string(x), r(s.rbegin(), s.rend());
            int y = stoi(s + r.substr(1));
            if (y >= N && isPrime(y)) {
                return y;
            }
        }
        return -1;
    }
    constexpr bool isPrime(const int num) const noexcept {
        if (num < 2 || num % 2 == 0) {
            return num == 2;
        }
        for (auto i = 3; i * i <= num; i += 2) {
            if (num % i == 0) {
                return false;
            }
        }
        return true;
    }
};
11700