#include <bits/stdtr1c++.h>

using namespace std;

typedef double ld;
ld a[505][505], b[2][505];
int main() {
    ios::sync_with_stdio(0);
	int n; cin >> n;
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cin >> a[j][i];
		}
		b[0][i] = 1.0/sqrt(n);
	}

	int iters = 500;
	while (iters--) {
		ld len = 0;
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				b[iters&1][i] += a[i][j] * b[(iters&1)^1][j];
			}
			len += b[iters&1][i] * b[iters&1][i];
		}

		len = sqrt(len);
		for (int i = 0; i < n; i++) {
			b[iters&1][i] /= len;
		}
	}

	ld sum = 0;
	for (int i = 0; i < n; i++) {
		sum += b[0][i];
	}
	cout << fixed << setprecision(8) << b[0][0]/sum << endl;
	return 0;
}