救救我

 #include<bits/stdc++.h>
using namespace std;
int n, a, b, sum;
bool z;
int hwss(int a) {
	for (int i = 2; i * i <= a; i++) {
		if (a % i == 0)	{
			return false;
		}
	}
	return true;
}
int main() {
	cin >> n;
	for (int i = 11; i <= n; i++) {
		a = i;  
		z = hwss(a);     
		if (z == 1) {
			while (i) {
				int yu = n % 10;
				sum = sum * 10 + yu;
				n /= 10;
				
			}


			if (sum == i) {

				b++;
			}

		}
	}
	cout << b;
	return 0;
}

怎么写回文数代码？