Hi, the illustration is implying that push1(6) will return -1, but that method does not return anything (void).
Type your question above this line.
Course: https://www.educative.io/collection/5642554087309312/5646276079124480
Lesson: https://www.educative.io/collection/page/5642554087309312/5646276079124480/5663850078666752