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