Pokémon Evolution You have recently caught N Pokémon and you also have M Pokémon candy bars. You can evolve any of your Pokémon by paying X candy bars. Alternatively, you can sell any of your Pokémon for a price of Y candy bars. You cannot sell an evolved Pokémon. Compute the maximum number of Pokémon you can evolve.

Standard input The first line contains 4 integers N M X Y.

Standard output The output should contain a single integer representing the maximum number of Pokémon you can evolve.