***CACHE IS NOT AT THE POSTED COORDINATES - DO NOT GO THERE***

Complete the above grid with the missing numbers (1 to 20) so that the adjacent numbers ONLY connect by moving north, south, east or west - there can be no diagonal moves.
C3 B4A4 A2 A2 C3 C2 D2 B1 . E3 C2 E1 C2 D2 B1 . A1 D4 A2 A2 E1 B4A2