Xiaoxiang has a directed graph with nnnpoints and mmmedges. At first, every point on this directed graph was white. Recently, Xiaoxiang wants to color every point on this directed graph black. He can carry out several rounds of dyeing, and the dyeing rules of each round are as follows: Dyeing In each dyeing round, Xiaoxiang can dye any number of points. In each dyeing round, a pair of different iii, jjjcannot appear, Let point iiican reach point jjj. Now, Xiaoxiang would like to ask you to calculate that every point on this directed graph can be dyed only after at least several rounds of dyeing.
Xiaoxiang has a directed graph with nnn points and mmm edges. At first, every point on this directed graph was white. Recently, Xiaoxiang wants to color every point on this directed graph black. He can carry out several rounds of dyeing, and the dyeing rules of each round are as follows: Dyeing In each dyeing round, Xiaoxiang can dye any number of points. In each dyeing round, a pair of different iii, jjj cannot appear, Let point iii can reach point jjj. Now, Xiaoxiang would like to ask you to calculate that every point on this directed graph can be dyed only after at least several rounds of dyeing.
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