private void solve() throws IOException {
		double n = nextDouble();

		double l = 0;
		double r = n;
		double eps = 0.00000001;

		for(int it = 0; it < 128; it++) {
			double p1 = l + (r - l) / 3.0;
			double p2 = r - (r - l) / 3.0;

			double v1 = p1 * p1;
			double v2 = p2 * p2;

			double d1 = Math.abs(n - v1);
			double d2 = Math.abs(n - v2);

			if(d1 - d2 > eps) {
				l = p1;
			} else if(d2 - d1 > eps) {
				r = p2;
			} else {
				l = p1;
				r = p2;
			}
		}

		out.println(l);
	}