构造回文数老是写错，这是写的暴力枚举

#include<bits/stdc++.h>
using namespace std;

int L, R;

bool range(int x) {
	return !(12 <= x && x <= 99) || (1000 <= x && x <= 9999) || (100000 <= x && x <= 999999);
}

bool palindrome(int x) {
	string str, rstr;
	str = to_string(x), rstr = str;
	reverse(rstr.begin(), rstr.end());
	return rstr == str;
}

bool prime(int x) {
	for (register int i = 3; i <= sqrt(x); ++i, ++i) {
		if (x % i == 0) {
			return 0;
		}
	}
	return 1;
}

int main() {
	scanf("%d %d", &L, &R);
	if (L % 2 == 0) {
		L++;
	}
	R = min(9989899, R);
	for (register int i = L; i <= R; ++i, ++i) {
		if (range(i) && palindrome(i) && prime(i)) {
			printf("%d\n", i);
		}
	}
	return 0;
}