Find the minimum possible length of the sum of $1999$ unit vectors in the coordinate plane whose both coordinates are nonnegative.
Problem
Source: Mongolia 1999 Teachers elementary level P6
Tags: vector, geometry, analytic geometry
Source: Mongolia 1999 Teachers elementary level P6
Tags: vector, geometry, analytic geometry
Find the minimum possible length of the sum of $1999$ unit vectors in the coordinate plane whose both coordinates are nonnegative.