mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    V, T, P = map(int, input().split())

    ok = 1
    ng = 10**22
    mid = (ok+ng)//2
    while ng - ok > 1:
        if mid <= V + V * P + (mid-2) // T + 1:
            ok = mid
        else:
            ng = mid
        mid = (ok+ng)//2
    print(ok)


if __name__ == '__main__':
    main()