Count Nested Direct Referrals Count | MYSQL, PHP

Hello, I am building a MLM website and need to be solve a SQL query using PHP which counts each user's direct referrals users. #The Maximum Allowed Referral user is 50 (Here 50 direct referral means 50 individual chains ). #Each chain consist of N level of users and direct referrals (each users allowed 50 direct referral). #For better understanding please check attached snapshot. #As per screenshot you would see 3 individual chains. in the right chain there would see two users which have 50 direct referrals and there is single user also in left chain and middle chain which have completed there 50 direct referrals. #Suppose the top user (TOP user is completed its 50 direct referrals). # I want to count the number of chains which have at least one user with 50 direct Referrals. (N number Deep). #As per the screen shot we can say the top user have 3 chains which have at least one users with 50 direct referrals.