def main():
    
    A, B, C = map(int, input().split())
    
    # N = 1

    for N in range(10): 
        N += 1
        number = 0
        if N * A > B:
            number = N * A - B
        else:
            number = N * A
        if number == C:
            print(N)
        else:
            print("-1")


if __name__ == '__main__':
    main()