Level 29

You see a room which is 10x10m wide (0x0 to 9x9).
Every square has the exact temperature of 26°C. We apply continuously 81°C heat to the field 6x4
What is the temperature (rounded to whole numbers) in the field 2x2 after 78 iterations according to the Gauss-Seidel iteration

Field in the beginning

26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626
26262626262626262626

Field after 4 iterations (rounded after 4th iteration)

4688999863
610131415171817126
8131618212734292010
8141822304668482914
91520253869150713717
9152025355374543416
9152024303945392713
8141821242831272010
610131517192018137
357891010963

Temperature in field 2x2 after 78 iterations: