#1
import math
c = 299792458

def rela_mass(m0, v):
    return m0 / (math.sqrt(1 - (v**2/c**2)))

#2

def has_empty(s, t):
    return s == '' or t == ''

#3

def near_zero(a,b,c):
    if abs(a) < abs(b):
        if abs(a) < abs(c):
            return a
        else:
            return c
    else:
        if abs(b) < abs(c):
            return b
        else:
            return c

#4

def add(x, y):
    num = x[0] * y[1] + y[0] * x[1]
    den = x[1] * y[1]
    return (num, den)