Subtraction with numeric_Std doesn't work

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i simply specify y1<=integer(x-y ) where all are declared as integer .Though x and y hold there corresponding values say 231 and 6, y1 displays only its maximum range 214748368.

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With the code as it is, this is impossible, as that would be out of range of the subtype and would cause an error.

And when i remove the subtype declaration it says unsigned is not directly visible.

This is because numeric_std and std_logic_arith both declare unsigned. And so it doesnt know which one to use. So Delete the non-standard std_logic_arith library like I said.