aisa koi fixed logic nahi hai ki jis zone ki train hai wahi apne link bheje. p4 to src ke bhi paas pehle se the lekin ise src p4 kabhi nahi mila. shuru se hwh hi p4 deta aya hai. sapt kranti me bgkt ka emd lagta hai jabhi uske paas apne khud ke emd spj shed me hai.
by the way ir me kahi bhi kuch bhi ho sakta hai, so both points are possible.;