"""
Google Code Jam Farewell Round C - Problem E

Author  : chaotic_iak
Language: PyPy (Python 3.9.10)
"""

################################################### SOLUTION

def initialize_solution():
    ...

def main():
    p,S = read(str)
    p = int(p)

    if p >= 4:
        for i in range(len(S)-1):
            if S[i] > S[i+1]:
                found = i
                ans = []
                if found == 0:
                    ans.extend(S[:p-1])
                    ans.append(S[p-1:])
                elif found == len(S)-2:
                    ans.append(S[:-(p-1)])
                    ans.extend(S[-(p-1):])
                elif p <= found+3:
                    ans.extend(S[:p-4])
                    ans.append(S[p-4:found])
                    ans.extend(S[found:found+2])
                    ans.append(S[found+2:])
                else:
                    ans.extend(S[:p-1])
                    ans.append(S[p-1:])
                write("POSSIBLE")
                write(*ans)
                return
        return "IMPOSSIBLE"

    if p == 3:
        mn = min(S)
        mx = max(S)
        if mn == mx:
            if len(S) == 3: return "IMPOSSIBLE"
            write("POSSIBLE")
            write(S[:2], S[2], S[3:])
            return
        if any(S[i] == mn for i in range(2, len(S))):
            found = min(i for i in range(2, len(S)) if S[i] == mn)
            if found == len(S)-1:
                write("POSSIBLE")
                write(S[:-2], S[-2], S[-1])
                return
            else:
                write("POSSIBLE")
                write(S[:found], S[found], S[found+1:])
                return
        if S[1] == mn and S[0] != mn:
            write("POSSIBLE")
            write(S[0], S[1], S[2:])
            return
        gone = (1 if S[-1] == mx else 0)
        streak = 0
        for i in range(len(S)-2, -1, -1):
            if S[i] == mx:
                streak += 1
                if streak > gone:
                    write("POSSIBLE")
                    write(S[:i], S[i:i+streak], S[i+streak:])
                    return
            else:
                gone += streak
                streak = 0
        return "IMPOSSIBLE"

    if p == 2:
        cl = [0]*26
        cr = [0]*26
        for c in S: cr[ord(c)-65] += 1
        lmn = 26
        rmx = max(i for i in range(26) if cr[i])
        for i in range(len(S)-1):
            c = ord(S[i])-65
            cl[c] += 1
            lmn = min(lmn, c)
            cr[c] -= 1
            while cr[rmx] == 0: rmx -= 1
            if lmn > rmx:
                write("POSSIBLE")
                write(S[:i+1], S[i+1:])
                return
            if lmn == rmx:
                share = min(cl[lmn], cr[lmn])
                if sum(cl) > share:
                    write("POSSIBLE")
                    write(S[:i+1], S[i+1:])
                    return
        return "IMPOSSIBLE"

############################################### PROBLEM TYPE

HAS_TESTCASES = True
INTERACTIVE = False
INTERACTIVE_WRONG_ANSWER = ""

#################################################### HELPERS

import sys

def read_str():
    ipt = input().strip()
    if INTERACTIVE and ipt == INTERACTIVE_WRONG_ANSWER:
        sys.exit()
    return ipt

def read(mapping=int):
    ipt = input().strip()
    if INTERACTIVE and ipt == INTERACTIVE_WRONG_ANSWER:
        sys.exit()
    return list(map(mapping, ipt.split()))

def write_str(obj, end="\n"):
    global OUTPUT
    OUTPUT.append(obj + end)

def write(*obj, sep=" ", end="\n"):
    global OUTPUT
    OUTPUT.append(sep.join(map(str, obj)) + end)

def flush():
    global OUTPUT
    print("".join(OUTPUT), end="", flush=True)
    OUTPUT = []

def solve_testcase():
    result = main()
    if result is not None:
        write(result)

OUTPUT = []
initialize_solution()
if HAS_TESTCASES:
    TOTAL_CASES = int(input())
else:
    TOTAL_CASES = 1
for CASE_NUMBER in range(TOTAL_CASES):
    write("Case #" + str(CASE_NUMBER+1) + ": ", end="")
    solve_testcase()
    flush()
flush()

READ_FROM_FILE = ""