Stripmine Computercraft

os.loadAPI("mine")
os.loadAPI("bridge")
os.loadAPI("torch")
os.loadAPI("back")
os.loadAPI("inventoryFull")
print("Pls enter Tunnel length:")
length = tonumber(read())
print("Pls enter site length:")
sites = tonumber(read())
minedshafts = 0
minedInSites = 0

for i=1,length do
mine.mine()
bridge.bridge()
mine.mine()
bridge.bridge()
mine.mine()
bridge.bridge()
turtle.turnLeft()
for i2=1,sites do
mine.mine()
bridge.bridge()
end
turtle.turnLeft()
turtle.turnLeft()
for i2=1,sites do
mine.mine()
bridge.bridge()
end
for i2=1,sites do
mine.mine()
bridge.bridge()
end
turtle.turnLeft()
turtle.turnLeft()
for i2=1,sites do
mine.mine()
bridge.bridge()
end
turtle.turnRight()
minedshafts = minedshafts +1
minedInSites = minedInSites + 1
if minedInSites == 2 then
torch.placetorch()
minedInSites = 0
end
if inventoryFull.full() then
back.backandreturn(minedshafts)
end
end
back.back(minedshafts)