#include<iostream>
#include<cmath>
using namespace std;

bool zhi(int num) {
	num = sqrt(num);
	for(int step = 2; step < num; step++) {
		if(num % step == 0)
			return false;
	}
	return true;
}

bool hw(int num) {
	int	tag = 1,s = 0,sum = 0;
	s = num;
	while(num) {
		sum += num % 10;
		sum *= 10;
		num /= 10;
	}
	sum /= 10;
	if(sum != s)
	return false;
	return true;
}

int main() {
	int n = 0,res = 0;
	cin>>n;
	for(int i=11;i<=n;i++){
		if(zhi(i)&&hw(i)){
			res++;
		}
	}
	cout<<res;
	return 0;
}

单独测试函数没有问题，测试样例也过了QWQ。。。但是为什么不对？？？