Problems with installation and use of webpack

step:
1. First, npm install webpack-g
2. Later, npm install webpack@1.15.0 was installed locally-- save-dev
3. Then execute webpack-v
4. Prompt: The CLI moved into a separate package: webpack-cli

Would you like to install webpack-cli? (That will run npm install -D webpack-cli)  (yes/NO)yes,yes.

5. The result given to me is: {Error: Cannot find module "webpack-cli"

at Function.Module._resolveFilename (module.js:547:15)
at Function.Module._load (module.js:474:25)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)
at runCommand.then.result (C:\Users\leon-Yang\AppData\Roaming\npm\node_modules\webpack\bin\webpack.js:62:14)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:188:7) code: "MODULE_NOT_FOUND" }
?webpack-cli.node_moduleswebpack-cli.
?