import sys

def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for j in range(b)] for i in range(a)]
def list4d(a, b, c, d, e): return [[[[e] * d for j in range(c)] for j in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
sys.setrecursionlimit(10 ** 9)
INF = 10 ** 19
MOD = 10 ** 9 + 7
EPS = 10 ** -10

def bfs(src):
    from collections import deque

    que = deque([src])
    dist = {}
    dist[src] = 0
    while que:
        u = que.popleft()
        if u % c == 0:
            v = u // c
            if v not in dist:
                dist[v] = dist[u] + b
                que.append(v)
        else:
            v = u // c * c
            if v not in dist:
                dist[v] = dist[u] + b
                que.append(v)
            if u < c*2:
                v = u - (c-1)
                if v not in dist:
                    dist[v] = dist[u] + b
                    que.append(v)
    return dist

for _ in range(INT()):
    a, b, c = MAP()

    if c == 1:
        print(-1)
        continue

    res = bfs(a)
    if 0 in res:
        print(res[0])
    else:
        print(-1)