weekly Time set

Hello,please help me.

Start time is the first Monday of each month.

Daily data are expressed by week,How to set the time?

for example:

input:5/1 100,5/2 200,5/3 100,5/4 200,5/5 200・・・6/30 100

want to output :May

            week 1 = 5/3(Mon)~5/9

            week 2 = 5/10~5/16

            week 3 = 5/17~5/23

            week 4 = 5/24~5/30

            week 5 = 5/31~6/6

             June

            week 1 = 6/7(Mon)~6/13            

            week 2 = 6/14~6/20

            week 3 = 6/21~6/27

            week 4 = 6/28~7/4