class Problem0570:
    def solve(this):
        a = (int(input()), "A")
        b = (int(input()), "B")
        c = (int(input()), "C")
        res = [a,b,c]
        res = sorted(res, reverse=True)

        for t in res:
            print(t[1])

if __name__ == "__main__":
    problem = Problem0570()
    problem.solve()