This circuit measures the parity of four qubits using an ancilla qubit.
```python
from qiskit import QuantumCircuit
# Create a circuit with 5 qubits and 1 classical bit
qc = QuantumCircuit(5, 1)
# Prepare arbitrary states on the first four qubits
qc.h([0, 1, 2, 3]) # Example: put qubits into superposition
# Use the fifth qubit as an ancilla to measure the parity of qubits 0-3
qc.cx(0, 4)
qc.cx(1, 4)
qc.cx(2, 4)
qc.cx(3, 4)
# Measure the ancilla qubit
qc.measure(4, 0)
```'Failed to run program: \'409 Client Error: Conflict for url: https://api.quantum.ibm.com/runtime/jobs. {"errors":[{"message":"You have reached the limit of 3 pending jobs. Please wait for a job to complete or cancel one before submitting anything new.","code":3458,"solution":"Wait until some previous jobs were finished. You can cancel pending jobs to run new jobs.","more_info":"https://docs.quantum-computing.ibm.com/errors"}]}\''