Codeforces task solution. https://i.imgur.com/iLLPRBq.jpg

solution.nim

from strutils import parseInt, split, join

let n = uint8(parseInt(readLine(stdin)))
var x_roads_asphalted: seq[uint8]
var y_roads_asphalted: seq[uint8]
var days: seq[uint8]
var counter: uint8 = 1
for i in uint8(1)..(n * n):
    let t = split(readLine(stdin), ' ')
    var x_road = uint8(parseInt(t[0]))
    var y_road = uint8(parseInt(t[1]))
    if not (x_road in x_roads_asphalted) and not (y_road in y_roads_asphalted):
        x_roads_asphalted.add(x_road)
        y_roads_asphalted.add(y_road)
        days.add(counter)
    counter += 1

echo(days.join(" "))