#!/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 z < b:
        if x < a or y < a or n-1-x < a or n-1-y < a:
            return "B"
        else:
            return "A"
    else:
        if x < a or y < a or n-1-x < a or n-1-y < a:
            return "C"
        else:
            return "P"

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