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You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").

Paragraph- Sent 1: In collaboration with Sigmund Freud and a small group of Freud's colleagues, Adler was among the co-founders of the psychoanalytic movement and a core member of the Vienna Psychoanalytic Society: indeed, to Freud he was "the only personality there".
Sent 2: He was the first major figure to break away from psychoanalysis to form an independent school of psychotherapy and personality theory, which he called individual psychology because he believed a human to be an indivisible whole, an individuum.
Sent 3: He also imagined a person to be connected or associated with the surrounding world.
Sent 4: This was after Freud declared Adler's ideas as too contrary, leading to an ultimatum to all members of the Society (which Freud had shepherded) to drop Adler or be expelled, disavowing the right to dissent (Makari, 2008).
Sent 5: Nevertheless Freud always took Adler's ideas seriously, calling them "... honorable errors.
Sent 6: Though one rejects the content of Adler's views, one can recognize their consistency and significance".
Sent 7: Following this split, Adler would come to have an enormous, independent effect on the disciplines of counseling and psychotherapy as they developed over the course of the 20th century (Ellenberger, 1970).
Sent 8: He influenced notable figures in subsequent schools of psychotherapy such as Rollo May, Viktor Frankl, Abraham Maslow and Albert Ellis.
Sent 9: His writings preceded, and were at times surprisingly consistent with, later neo-Freudian insights such as those evidenced in the works of Otto Rank, Karen Horney, Harry Stack Sullivan and Erich Fromm, some considering that it would take several decades for Freudian ego psychology to catch up with Adler's ground-breaking approach.
Sent 10: Adler emphasized the importance of equality in preventing various forms of psychopathology, and espoused the development of social interest and democratic family structures for raising children.
Sent 11: His most famous concept is the inferiority complex which speaks to the problem of self-esteem and its negative effects on human health (e.g.
Sent 12: sometimes producing a paradoxical superiority striving).
Sent 13: His emphasis on power dynamics is rooted in the philosophy of Nietzsche, whose works were published a few decades before Adler's.
Sent 14: However, Adler's conceptualization of the "Will to Power" focuses on the individual's creative power to change for the better.
Sent 15: Adler argued for holism, viewing the individual holistically rather than reductively, the latter being the dominant lens for viewing human psychology.
Sent 16: Adler was also among the first in psychology to argue in favor of feminism, and the female analyst, making the case that power dynamics between men and women (and associations with masculinity and femininity) are crucial to understanding human psychology (Connell, 1995).
Sent 17: Adler is considered, along with Freud and Jung, to be one of the three founding figures of depth psychology, which emphasizes the unconscious and psychodynamics (Ellenberger, 1970; Ehrenwald, 1991); and thus to be one of the three great psychologists/philosophers of the twentieth century. 
Question: Who was the figure that developed the school of psychotherapy called individual psychology?.
Output:
1, 2.