#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;

#[allow(unused_macros)]
macro_rules! debug {
    ($($e:expr),*) => {
        #[cfg(debug_assertions)]
        $({
            let (e, mut err) = (stringify!($e), std::io::stderr());
            writeln!(err, "{} = {:?}", e, $e).unwrap()
        })*
    };
}

fn main() {
    let q = read::<usize>();
    for i in 0..q {
        let v = read_vec::<i64>();
        let (a, b, c) = (v[0], v[1], v[2]);
        if c == 1 {
            println!("-1");
            continue;
        }
        let mut ans = 0;
        let mut a = a;
        while a != 0 {
            if a < c {
                a = 0;
                ans += 1;
            } else if a < 2 * c - 1 {
                a = 0;
                ans += 2;
            } else if a % c > 0 {
                a -= a % c;
                ans += 1;
            } else {
                a /= c;
                ans += 1;
            }
        }
        println!("{}", ans * b);
    }
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}