import sys
from collections import deque, Counter
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

a, b, c = mi()
f = False
for i in range(1, 10 ** 6):
    now = i
    now *= a
    if now - b > 0:
        now -= b
    else:
        pass
    if now == c:
        f = True
        print(i)

if not f:
    print(-1)