Estimate the length of the following river.
Amazon
The length of the Amazon River, which is located in South America, is estimated to be approximately 6,400 kilometers or 3,976 miles long. However, exact measurements may vary due to its natural changes over time.
Complete the following task based on the instruction and optional input provided.### Instruction:
Estimate the length of the following river.

### Input:
Amazon

### Output:
The length of the Amazon River, which is located in South America, is estimated to be approximately 6,400 kilometers or 3,976 miles long. However, exact measurements may vary due to its natural changes over time.