For the following poem, write the rhyme scheme.
Once upon a time there was a bear
it roamed around with no one to care
Trudging through the forest day and night
Without food it couldn't take flight
The rhyme scheme of this poem is AABB.
Complete the following task based on the instruction and optional input provided.### Instruction:
For the following poem, write the rhyme scheme.

### Input:
Once upon a time there was a bear
it roamed around with no one to care
Trudging through the forest day and night
Without food it couldn't take flight

### Output:
The rhyme scheme of this poem is AABB.