After leaving his island, Tintin seeked the help of the great scientist Dr. Calculus who stayed in his research island. When he landed on the island, he notices a map of 25 labs, aligned in a 5x5 pattern, of which a few labs were burned(Coloured in figure). Only 15 labs numbered from `#1` to `#15` are not burnt. He noticed the map, but realised that the lab numbers were missing from it. Instead, an instruction read “The distance from lab #1 to lab #2 will be less than the distance from lab `#2` to lab`#3`, which is less than the distance from lab #3 to lab `#4`, and so on”. Also, only the intact labs were numbered. Find out the value of a+b (where a and b are the lab numbers). Note : Distance is calculated from the centre of one lab to the centre of another.