Farthest vertex

Given an undirected graph, compute the vertex which is farthest from vertex 0.

Input

Input consists of several graphs. Each graph starts with the number of vertices $n$ and the number of edges $m$ , followed by $m$ pairs $x$ $y$ that correspond to and edge between vertices $x$ and $y$ . It holds that $1 \le n \le 10^4$ , $0 \le m \le 5n$ , vertices are numbered from $0$ to $n-1$ , and there are neither repeated edges nor edges of the form $x$ $x$ .

Output

For each graph, write the vertex which is farthest from vertex 0. In case of a tie, choose the smallest vertex. Ignore vertices that are not reachable from 0.

Problem information

Author: Salvador Roura

Generation: 2026-01-25T22:42:05.603Z