Password Generator

After a series of leaks of confidential information, the public began to think seriously about which passwords to use. For example, the password <<11111>> is simple and should not be used. But how do you tell whether a password is good?

The Business Process Standardization Foundation conducted a study showing that a good password must be long enough and contain characters of different kinds. The study showed that a good password must have exactly $n$ characters. The password must consist of uppercase and lowercase Latin letters and digits, and satisfy the following requirements:

• the password must contain at least $a$ uppercase letters;
• the password must contain at least $b$ lowercase letters;
• the password must contain at least $c$ digits;
• the password must not contain two identical consecutive characters.

Realizing that users would find it uncomfortable to invent a password satisfying all these requirements, the Foundation's staff decided to write a program to help users with this task.

Help the Foundation: write a program that, given the parameters, generates a suitable password.

The first line of the input contains the integer $n$, the required password length ($1 \le n \le 100$). The second line contains the non-negative integers $a$, $b$ and $c$, the minimum required number of uppercase letters, lowercase letters and digits, respectively ($a + b + c \le n$).

In a single line, output any good password. Only uppercase and lowercase Latin letters and digits may be used.