The Australian government would like to assess the impact of employment in different sectors on the number of days of parental leave taken by men. They ask 13 men employed in the public sector who had recently had a child, "how many days of parental leave have you taken?". They also ask 6 men in the private sector the same question. The public sector survey has a sample mean of 12.23 and standard deviation of 4, while the private sector survey has a sample mean of 30 and standard deviation of 5.

What is the total number of individuals surveyed in this study?