React Hook "useState" is called in function "app" which is neither a React function component or a custom React Hook function react-hooks/rules-of-hooks

capitalize 
const App

//Try to capitalize 'app' like
const App = props => {...}

export default App;

 React Hook "React.useState" is called in function "placeItem" which is neither a React function component or a custom React Hook function  react-hooks/rules-of-hooks

answer :- function name must be start with capital letter