import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int q = Integer.parseInt(sa[0]);
		for (int i = 0; i < q; i++) {
			sa = br.readLine().split(" ");
			long a = Integer.parseInt(sa[0]);
			long b = Integer.parseInt(sa[1]);
			long c = Integer.parseInt(sa[2]);

			if (c == 1) {
				System.out.println(-1);
			} else {
				long ans1 = 0;
				while (a >= c * c) {
					if (a % c > 0) {
						ans1++;
					}
					a /= c;
					ans1++;
				}
				ans1 *= b;
				long ans2 = Long.MAX_VALUE;
				for (int j = 0; j < 3; j++) {
					long x = (long) Math.pow(c, j);
					if (x > a) {
						break;
					}
					long val1 = j;
					long val2 = (a / x + c - 2) / (c - 1);
					long val3 = (a % x + c - 2) / (c - 1);
					long val = val1 + val2 + val3;
					val *= b;
					ans2 = Math.min(ans2, val);
				}
				System.out.println(ans1 + ans2);
			}
		}
		br.close();
	}
}