Revert "modified makefile to compile newly added main.cpp"

This reverts commit a34538c66b1c5553009cd5499f83a1d27cfc8b78.
Revert "Revert "modified makefile to compile newly added main.cpp""

This reverts commit 9e7d2d1fa23ef0425a4a01938745b68470d969a1.
Revert "modified makefile to compile newly added main.cpp"

This reverts commit a34538c66b1c5553009cd5499f83a1d27cfc8b78.
Revert "Revert "modified makefile to compile newly added main.cpp""

This reverts commit 4dbe73b2708a2c025a712bdfaa64638638521808.
modified makefile to compile main.cpp