Table:
David Letterman

Letterman in May 2016

Birth name	David Michael Letterman
Born	(1947-04-12) April 12, 1947 (age 78)
Indianapolis, Indiana, U.S.
Medium	Stand-up, television, film
Alma mater	Ball State University
Years active	1970–present
Genres	Observational comedy, satire, deadpan, self-deprecation
Subject(s)	American culture, politics, everyday life, current events, human behavior
Spouse

Michelle Cook

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(m. 1968; div. 1977)​

Regina Lasko

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(m. 2009)​

Children	1
Notable works and roles

The David Letterman Show (host; 1980)

Late Night with David Letterman (host; 1982–1993)

Late Show with David Letterman (host; 1993–2015)

My Next Guest (2018–)

Signature

Given this table, what is the content of the cell situated at the 1st row and the 1st column? The target cell value should be presented in the JSON format of {"row_id":"m", "column_id":"n", "cell_value":"<Corresponding Cell Value>"}, e.g., {"row_id":"10", "column_id":"3", "cell_value":"District"}.

The target cell value in the 1st row and the 1st column is {"row_id":"1", "column_id":"1", "cell_value":"David Letterman"}.