This utility calculates the sample size required to detect a statistically
significant difference between two sample means with specified levels of confidence and
power, assuming unequal variances and allowing for unequal sample sizes between groups.

Inputs are the assumed true values for the two means and their variances,
the desired level of confidence and the desired power for the detection of a significant difference. By default, calculations
assume that a two-tailed statistical test will be used, but a one-tailed test can also be
specified if preferred.

The program outputs the sample size required to detect the specified difference
with desired power and confidence, for a one-tailed or two-tailed statistical test,
as specified.