测试样例都没过 dalao帮帮我

#include <iostream>
using namespace std ;
long long n , m , l , r ;
int main (){
	cin >> n >> m ;
	long long arr[1010] = { 0 , 0 } ;
	for ( int i = 2 ; i <= m ; i++ ){
		for ( int j = 2 ; j <= sqrt ( i ) ; j++ ){
			if ( i % j == 0 ) flag = 1 ; break ;
		}
		if ( flag ) arr[i] = arr[i - 1] + 1 ; 
		else arr[i] = arr[i - 1] ;
	}
	for ( int i = 1 ; i <= n ; i++ ){
		cin >> l >> r ;
		if ( l < 1 || r < 1 || l > m || r > m ) cout << "Crossing the line" << endl  ; continue ; 
		cout << arr[r] - arr[l - 1] << endl ;
		
	}
	return 0 ; 
}