Trying to generate 5 random items, sometimes generate 4. (Python)

import random

twoDimMap = [["H","-","-","-","-","-"],["-","-","-","-","-","-"],["-","-","-","-","-","-"],["-","-","-","-","-","-"],["-","-","-","-","-","-"],["-","-","-","-","-","-"]]

items = 0

while items<=4:
    test = random.randrange(0,3)
    if test == 0:
        twoDimMap[random.randrange(0, 5)][random.randrange(0, 5)] = "S"
    if test ==1:
         twoDimMap[random.randrange(0, 5)][random.randrange(0, 5)] = "R"
    if test == 2:
        twoDimMap[random.randrange(0, 5)][random.randrange(0, 5)] = "*"
    #I couldn't think of an easier way to do this
    if twoDimMap[0][0] != "H":
        twoDimMap[0][0]="H"
        items-=1
    items+=1

print(twoDimMap)

Title explains it all pretty much (even though I know it isn't too descriptive :/), I am trying to make a game where the hero starts on the map at position [0],[0]. I can't work out why the hell I'm sometimes generating fewer items than other times.