When run truffle compile, I get the error:
Compiling ./contracts/Migrations.sol...
/home/edureka/t/contracts/Migrations.sol:16:32: TypeError: Type int256 is not implicitly convertible to expected type uint256.
    last_completed_migration = completed;
                               ^-------^
,/home/edureka/t/contracts/Migrations.sol:21:27: TypeError: Invalid type for argument in function call. Invalid implicit conversion from uint256 to int256 requested.
    upgraded.setCompleted(last_completed_migration);
                          ^----------------------^
How to solve this?