Getting result of dynamic SQL into a variable for sql-server

Question

DECLARE @sqlCommand NVARCHAR(1000)
DECLARE @count INT
DECLARE @city VARCHAR(75)
SET @city = 'New York'

SET @sqlCommand = 'SELECT @cnt=COUNT(*) FROM customers WHERE City = @city'
EXECUTE sp_executesql @sqlCommand, N'@city nvarchar(75), @cnt int OUTPUT', @city = @city, @cnt = @count OUTPUT

SELECT @count

dynamic version

    ALTER PROCEDURE [dbo].[ReseedTableIdentityCol](@p_table varchar(max))-- RETURNS int
    AS
    BEGIN
        -- Declare the return variable here
       DECLARE @sqlCommand nvarchar(1000)
       DECLARE @maxVal INT
       set @sqlCommand = 'SELECT @maxVal = ISNULL(max(ID),0)+1 from '+@p_table
       EXECUTE sp_executesql @sqlCommand, N'@maxVal int OUTPUT',@maxVal=@maxVal OUTPUT
       DBCC CHECKIDENT(@p_table, RESEED, @maxVal)
    END


exec dbo.ReseedTableIdentityCol @p_table='Junk'

You've probably tried this, but are your specifications such that you can do this?

DECLARE @city varchar(75)
DECLARE @count INT
SET @city = 'London'
SELECT @count = COUNT(*) FROM customers WHERE City = @city

this could be a solution?

declare @step2cmd nvarchar(200)
DECLARE @rcount NUMERIC(18,0)   
set @step2cmd = 'select count(*) from uat.ap.ztscm_protocollo' --+ @nometab
EXECUTE @rcount=sp_executesql @step2cmd
select @rcount