SPAM CANS
PART 1:
-you are standing next to a pile of Spam cans
-these are sufficient in number to complete this puzzle!
-you wish to walk a distance of 100 miles (straight path)
-you can walk 20 miles per day
-to keep up your strength, you need to eat a Spam can per mile
-you can carry 60 cans, no more
How long (minimum) will it take you to reach your destination
if you can hide cans at points 20, 40, 60 and 80 only?

PART 2:
Ok; that was easy: just a warmup, right?
This time, you can hide your cans anywhere you want.
What is the minimum number of cans you need in order
to reach your destination?
Caution: you cannot hide a part-Spam-can anywhere: too many ants.