Complete the following Menu Windows Form program. Write the code for the Calculate menu according to the following instructions. The user should enter the marks for subject1 and subject2 in textbox1 and textbox2 respectively. If the user missed to enter the marks, then appropriate error message should be displayed. The mark should be between 0 and 100. When the Total menu clicked, the total mark should be calculated and the result should be placed in label1. When the Average menu clicked, the average of both marks should be calculated and the result should be placed in label2.