题目描述

Farmer John and Bessie are playing games again. This one has to do
with troughs of water.

Farmer John has hidden N (1 1 trough is filled

From question 1, we know trough 1 is filled.
From question 3, we then know trough 4 is empty.
From question 4, we then know that trough 3 is filled.
From question 2, we then know that trough 2 is empty.

求N位二进制数X，使得给定的M个数，满足X and Bi=Ci ,Bi ci分别是读入的两个数

输入格式

• Line 1: Two space-separated integers: N and M

• Lines 2..M+1: A subset of troughs, specified as a sequence of
  contiguous N 0's and 1's, followed by a single integer that is
  the number of troughs in the specified subset that are filled.

输出格式

• Line 1: A single line with:

  • The string "IMPOSSIBLE" if there is no possible set of filled troughs
    compatible with Farmer John's answers.

  • The string "NOT UNIQUE" if Bessie cannot determine from the given data
    exactly what troughs are filled.

  • Otherwise, a sequence of contiguous N 0's and 1's specifying
    which troughs are filled.

样例输入

4 4
1000 1
0110 1
1001 1
0011 1

样例输出

1010

提示

Silver