Problem: Little Timofey likes integers a lot. Unfortunately, he is very young and can't work with very big integers, so he does all the operations modulo his favorite prime m. Also, Timofey likes to look for arithmetical progressions everywhere.

One of his birthday presents was a sequence of distinct integers a1, a2, ..., an. Timofey wants to know whether he can rearrange the elements of the sequence so that is will be an arithmetical progression modulo m, or not.

Arithmetical progression modulo m of length n with first element x and difference d is sequence of integers x, x + d, x + 2d, ..., x + (n - 1)·d, each taken modulo m.

Input

The first line contains two integers m and n (2 ≤ m ≤ 109 + 7, 1 ≤ n ≤ 105, m is prime) — Timofey's favorite prime module and the length of the sequence.

The second line contains n distinct integers a1, a2, ..., an (0 ≤ ai < m) — the elements of the sequence.

Output

Print -1 if it is not possible to rearrange the elements of the sequence so that is will be an arithmetical progression modulo m.

Otherwise, print two integers — the first element of the obtained progression x (0 ≤ x < m) and its difference d (0 ≤ d < m).

If there are multiple answers, print any of them.

Examples

Input

17 5
0 2 4 13 15


Output

13 2


Input

17 5
0 2 4 13 14


Output

-1


Input

5 3
1 2 3


Output

3 4

Solution (in PYTHON3):

Solution:
import bisect
import copy
import decimal
import fractions
import heapq
import itertools
import math
import random
import sys
from collections import Counter,deque,defaultdict
from functools import lru_cache,reduce
from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max
def _heappush_max(heap,item):
    heap.append(item)
    heapq._siftdown_max(heap, 0, len(heap)-1)
def _heappushpop_max(heap, item):
    if heap and item < heap[0]:
        item, heap[0] = heap[0], item
        heapq._siftup_max(heap, 0)
    return item
from math import e, gcd as GCD, modf
read=sys.stdin.read
readline=sys.stdin.readline
readlines=sys.stdin.readlines

def Extended_Euclid(n,m):
    stack=[]
    while m:
        stack.append((n,m))
        n,m=m,n%m
    if n>=0:
        x,y=1,0
    else:
        x,y=-1,0
    for i in range(len(stack)-1,-1,-1):
        n,m=stack[i]
        x,y=y,x-(n//m)*y
    return x,y

class MOD:
    def __init__(self,mod):
        self.mod=mod
    
    def Pow(self,a,n):
        a%=self.mod
        if n>=0:
            return pow(a,n,self.mod)
        else:
            assert math.gcd(a,self.mod)==1
            x=Extended_Euclid(a,self.mod)[0]
            return pow(x,-n,self.mod)

    def Build_Fact(self,N):
        assert N>=0
        self.factorial=[1]
        for i in range(1,N+1):
            self.factorial.append((self.factorial[-1]*i)%self.mod)
        self.factorial_inv=[None]*(N+1)
        self.factorial_inv[-1]=self.Pow(self.factorial[-1],-1)
        for i in range(N-1,-1,-1):
            self.factorial_inv[i]=(self.factorial_inv[i+1]*(i+1))%self.mod
        return self.factorial_inv

    def Fact(self,N):
        return self.factorial[N]

    def Fact_Inv(self,N):
        return self.factorial_inv[N]

    def Comb(self,N,K):
        if K<0 or K>N:
            return 0
        s=self.factorial[N]
        s=(s*self.factorial_inv[K])%self.mod
        s=(s*self.factorial_inv[N-K])%self.mod
        return s


M,N=map(int,readline().split())
A=list(map(int,readline().split()))
set_A=set(A)
MD=MOD(M)
if N==M:
    print(0,1)
    exit()
if 2*N<M:
    if N==1:
        print(A[0],0)
        exit()
    a=(A[0]-A[1])%M
    cnt=0
    for i in range(N):
        if (A[i]+a)%M in set_A:
            cnt+=1
    d=a*MD.Pow(N-cnt,-1)%M
    cnt=0
    for i in range(N):
        if (A[i]-d)%M in set_A:
            cnt+=1
        else:
            ans=A[i]
    if cnt==N-1:
        print(ans,d)
        exit()
else:
    A=[a for a in range(M) if not a in set_A]
    N=len(A)
    if N==1:
        print((A[0]+1)%M,1)
        exit()
    set_A=set(A)
    a=(A[0]-A[1])%M
    cnt=0
    for i in range(N):
        if (A[i]+a)%M in set_A:
            cnt+=1
    d=a*MD.Pow(N-cnt,-1)%M
    cnt=0
    for i in range(N):
        if (A[i]+d)%M in set_A:
            cnt+=1
        else:
            ans=A[i]
    if cnt==N-1:
        print((ans+d)%M,d)
        exit()
print(-1)