40分怎么做

#include <iostream>
using std::cout,std::cin;
bool zhishu(int n){
    if(n <= 1) return 0;
    if(n == 2) return 1;
    for(int i = 2;i < n;i ++){
        if(n % i == 0) return 0;
    }
    return 1;
}
int main() {
    int x,y,cnt=0;
    cin >> x >> y;
    for(int i = x;i <= y;i ++){
        if(zhishu(i)) cnt++;
    }
    cout << cnt;
    return 0;
}