kangaroo

def kangaroo(x1, v1, x2, v2):
    # solve the equations
    # x = x1 + v1*t
    # x = x2 + v2*t
    # you get t = (x1 - x2)/(v2 - v1)

    if v1 == v2:    # if they have same speed they can meet only if
        print('YES' if x1 == x2 else 'NO')  # they start out together
    else:       # otherwise they always meet (possibly in the past, t < 0)
        t = (x1 - x2) // (v2 - v1)
        print('YES' if t >= 0 else 'NO') # but we only want t >= 0