PRIME1-What’s Wrong with my Code?

I’ve trying to get this to work, but I’m unable to find anything wrong. Does anybody know why it’s not working?

#include <iostream>
using namespace std;

bool isprime(int n)
{

if (n <= 1) {
	return false;

}
if (n <= 3) {
	return true;
}


if (n % 2 == 0 || n % 3 == 0) {
	return false;
}

for (int i = 5; i*i <= n; i = i + 6) {
	if (n%i == 0 || n % (i + 2) == 0) {
		return false;
	}
}
return true;
}

void primes(int num1, int num2) {
for (int i = num1; i <= num2; i++) {
	if (isprime(i)) {
		cout << i << endl;
	}
}
}
int main() {
int size;
cin >> size;
int num1;
int num2;

for (int i = 0; i <= size; i++) {
	cin >> num1 >> num2;
	primes(num1, num2);

}

return 0;
}