import math


def distL2(x1,y1,x2,y2):
    """Compute the L2-norm (Euclidean) distance between two points.

    The distance is rounded to the closest integer, for compatibility
    with the TSPLIB convention.

    The two points are located on coordinates (x1,y1) and (x2,y2),
    sent as parameters"""
    xdiff = x2 - x1
    ydiff = y2 - y1
    return int(math.sqrt(xdiff*xdiff + ydiff*ydiff) + .5)