Re-arrange these sentences to form a meaningful story.
They were walking in the forest. Suddenly, they saw a little house. It was a very old house.
They were walking in the forest when suddenly, they saw a little house. It was a very old house.
Complete the following task based on the instruction and optional input provided.### Instruction:
Re-arrange these sentences to form a meaningful story.

### Input:
They were walking in the forest. Suddenly, they saw a little house. It was a very old house.

### Output:
They were walking in the forest when suddenly, they saw a little house. It was a very old house.