IMO 1986 LL MON54

Find the least integer n with the following property: For any

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IMO 1986 LL MON54

Origin: MON

Problem

Find the least integer n with the following property: For any set V of 8 points in the plane, no three lying on a line, and for any set E of n line segments with endpoints in V , one can find a straight line intersecting at least 4 segments in E in interior points.