excel formula - its urgent

Hi friends,

I need help on a formula in which i want to count the text in a column if a particular criteria is fulfilled in another column. For example,   the data is as given below:

Name                    yes/no

nitin                       yes

sanjeev                no

sanjeev                yes

nitin                       yes

nitin                       no

now i want a formula in which the result should be total number of yes from yes/no column if there is nitin in name column i.e., nitin = 2, sanjeev = 1.

Please suggest the formula.

Thanks in advance.