Problem:
RMQ and RUQ

Write a program which manipulates a sequence A = {a0, a1, . . . , an−1} with the following operations:

update(s, t, x): change as, as+1, ..., at to x.

find(s, t): report the minimum element in as, as+1, ..., at.

Note that the initial values of ai (i = 0, 1, . . . , n−1) are 231-1.

Input

n q
query1
query2
:
queryq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, ith query queryi is given in the following format:

0 s t x

or

1 s t

The first digit represents the type of the query. '0' denotes update(s, t, x) and '1' denotes find(s, t).

Output

For each find operation, print the minimum value.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

0 ≤ s ≤ t < n

0 ≤ x < 231−1

Sample Input 1

3 5
0 0 1 1
0 1 2 3
0 2 2 2
1 0 2
1 1 2

Sample Output 1

1
2

Sample Input 2

1 3
1 0 0
0 0 0 5
1 0 0

Sample Output 2

2147483647
5

Solution in Ruby (judge verdict: Accepted)

class SegmentTree
  
  def initialize
    @N=2**17
    @INF=2**31-1
    @seg=Array.new(2*@N-1){@INF}
    @lazy=Array.new(2*@N-1){-1}
  end
  
  def refresh(i, l, r)
    unless @lazy[i]==-1
      @seg[i]=@lazy[i]
      if r-l>1
        @lazy[2*i+1]=@lazy[i]
        @lazy[2*i+2]=@lazy[i]
      end
      @lazy[i]=-1
    end
  end
  
  def update(a, b, x, i=0, l=0, r=@N)
    refresh(i, l, r)
    if b<=l or r<=a
      return
    elsif a<=l and r<=b
      @lazy[i]=x
      refresh(i, l, r)
    else
      m=(r+l)/2
      update(a, b, x, 2*i+1, l, m)
      update(a, b, x, 2*i+2, m, r)
      @seg[i]=[@seg[2*i+1], @seg[2*i+2]].min
    end
  end
  
  def min(a, b, i=0, l=0, r=@N)
    refresh(i, l, r)
    if b<=l or r<=a
      @INF
    elsif a<=l and r<=b
      @seg[i]
    else
      m=(r+l)/2
      vl=min(a, b, 2*i+1, l, m)
      vr=min(a, b, 2*i+2, m, r)
      [vl, vr].min
    end
  end
  
end

st=SegmentTree.new
n, q=gets.split.map(&:to_i)
q.times do
  query=gets.chomp
  case query[0].to_i
  when 0
    c, s, t, x=query.split.map(&:to_i)
    st.update(s, t+1, x)
  when 1
    c, s, t=query.split.map(&:to_i)
    puts st.min(s, t+1)
  end
end