def loneliest(string):
    string_test = string.strip()
    string_test = list(string_test)
    string_dict = {}
    string_out = list()

    i = 0
    for symbol in string_test:
        if symbol == " ":
            i += 1
        else:
            string_dict[symbol] = i
            i = 0

    i = 0
    for symbol in reversed(string_test):
        if symbol == " ":
            i += 1
        else:
            string_dict[symbol] += i
            i = 0

    string_test_keys = list(string_dict.keys())
    string_test_values = list(string_dict.values())

    i = 0
    for value in string_test_values:
        if value == max(string_test_values):
            string_out.append(string_test_keys[i])
        i += 1

    print(string, "=>", string_out)
            
loneliest("a b  c")
loneliest("a bcs           d k")
loneliest("    a b  sc     p     t   k")
loneliest("a  b  c  de")
loneliest("     a  b  c de        ")
loneliest("abc")