Input (grade 13): At Kazan University, Lobachevsky was influenced by professor Johann Christian Martin Bartels (1769 1833), a former teacher and friend of German mathematician Carl Friedrich Gauss.
Output (grade 10): At Kazan University, Lobachevsky was influenced by professor Johann Christian Martin Bartels (1769 1833). Bartels was a former teacher and friend of German mathematician Carl Friedrich Gauss.