"cout" cannot be used

ROOT
9

Thank you for your kindness many times.
Paste the source code below.

#include <iostream>
#define N 1000

using namespace std;

int kadai211(void) {
	double cnt = 0.0;
	for (int i = 0; i < N; i++) {
		double x = (double)rand() / RAND_MAX;
		double y = (double)rand() / RAND_MAX;

		if ((x * x + y * y) <= 1) {
			cnt += 1.0;
		}
	}
	cout << "pi:" << cnt / N * 4.0 << endl;
return 0;
}