编译失败,求救！

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

int main () {
	int A, B, cut = 0;
	cin >> A >> B;
	for (int i = A; i <= B; ++i) {
		if (isPrime(i)) 
		    cut++;
	}
	cout >> cut;
	return 0;
}