A clever dog named Negro has grasped the concept of commerce. Negro, who has lived on the campus of Colombia’s Diversified Technical Education Institute of Monterrey Casanare for the past five years, has discovered that if he ventures into the campus store with a leaf, in exchange he will receive a cookie.

The Dodo reports that Negro is cared for by the school’s faculty. They provide shelter, food, water, and tons of love and attention for the pup, who would watch the students in the university shop exchanging money for food and goods until he came to his stunning realization.

More from The Daily Meal

"He would go to the store and watch the children give money and receive something in exchange," teacher Angela Garcia Bernal told the news outlet. "Then one day, spontaneous, he appeared with a leaf in his mouth, wagging his tail and letting it be known that he wanted a cookie."

The leaf-cookie exchange has become a daily occurrence for extremely good boy Negro, who is a “paying” customer just like everybody else. "He comes for cookies every day," Gladys Barreto, a longtime store attendant, revealed to The Dodo. "He always pays with a leaf. It is his daily purchase."

"When you first see it, you almost want to cry," Bernal explained. "He's found a way to make himself understood. He's very intelligent."

This article originally appeared on The Daily Meal.