P25047 [AtCoder] Two Faced Edges
NOI
题目描述

Problem Statement

You are given a directed graph with N vertices and M edges.
The vertices are numbered 1, 2, ..., N, and the edges are numbered 1, 2, ..., M.
Edge i points from Vertex a_i to Vertex b_i.
For each edge, determine whether the reversion of that edge would change the number of the strongly connected components in the graph.
Here, the reversion of Edge i means deleting Edge i and then adding a new edge that points from Vertex b_i to Vertex a_i.

Input

Input is given from Standard Input in the following format:
N M
a_1 b_1
a_2 b_2
:
a_M b_M

Output

Print M lines. In the i-th line, if the reversion of Edge i would change the number of the strongly connected components in the graph, print diff; if it would not, print same.

Constraints

  • $2 \leq N \leq 1000$
  • $1 \leq M \leq 200,000$
  • $1 \leq a_i, b_i \leq N$
  • $a_i \neq b_i$
  • If $i \neq j$, then $a_i \neq a_j$ or $b_i \neq b_j$.

Sample Input 1

3 3
1 2
1 3
2 3

Sample Output 1

same
diff
same

The number of the strongly connected components is 3 without reversion of edges, but it will become 1 if Edge 2 is reversed.

Sample Input 2

2 2
1 2
2 1

Sample Output 2

diff
diff

Reversion of an edge may result in multiple edges in the graph.

Sample Input 3

5 9
3 2
3 1
4 1
4 2
3 5
5 3
3 4
1 2
2 5

Sample Output 3

same
same
same
same
same
diff
diff
diff
diff

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
3 3 1 2 1 3 2 3
样例输出
same diff same