use std::io::Read;

fn main() {
    let mut all_data = String::new();
    std::io::stdin().read_to_string(&mut all_data).ok();
    let mut all_data = all_data.trim().split('\n').map(|s| s.trim());
    let q: usize = all_data.next().unwrap().parse().unwrap();
    all_data.take(q).map(|s| s.split_whitespace().map(|i| i.parse().unwrap()).collect::<Vec<usize>>()).for_each(|abc| {
        let mut a = abc[0];
        let b = abc[1];
        let c = abc[2];
        if c == 1 {
            println!("{}", -1);
        } else {
            let mut count = 0;
            while a > 2*c - 2 {
                count += if a % c == 0 { 0 } else { 1 };
                a /= c;
                count += 1;
            }
            if a < c {
                count += 1;
            } else {
                count += 2;
            }
            println!("{}", b * count);
        }
    });
}