Kopecks for Blintzes

Shavuot is approaching, but Gitele and Yankl have no money to buy ingredients for blintzes. So they come up with a plan. Every day, they''ll each put a coin into the empty trunk. By Shvuot, they should have enough coins to buy the ingredients. But will they be able to stick to their plan and provide their family with delicious blintzes for Shavuot?