#!/usr/bin/env python3
import sys

n = int(sys.argv[1])
a = int(sys.argv[2])
b = int(sys.argv[3])

def f(x,y,z):
    if x < a and y < b:
        return "B"
    if x >= a and y < b:
        return "A"
    if x >= a and y >= b:
        return "P"
    if x < a and y >= b:
        return "C"

print(n)
for x in range(n):
    print("-")
    for y in range(n):
        print("".join([f(x,y,z) for z in range(n)]))