An engineer who is studying the tensile strength of a steel alloy intended for use in golf club shafts knows that tensile strength is approximately normally distributed with sigma=68. She wants to test whether the mean tensile strength is 3,530 psi or not at the level of significance (alpha) of 0.01. She wants to guarantee that the power of the test is 80%. If the true population mean is 3,492 psi, what sample size should she choose? (provide your answer with no decimal places after rounding appropriately)