import json


def calculate_average_age(records):
    try:
        total_age = 0
        for record in records:
            total_age += record["age"]
        average_age = total_age / len(records)
    except Exception:
        raise RuntimeError("Vypocet selhal!") from None
    return average_age


def main():
    # Vstup, na kterém to nefunguje:
    vstup = '[{"name": "Alice", "age": 25}, {"name": "Bob", "age": 30}, {"name": "Charlie", "age": "35"}]'
    
    # Vstup, na kterém to funguje:
    #vstup = '[{"name": "TEST", "age": 25}]'
    people_data = json.loads(vstup)

    avg_age = calculate_average_age(people_data)
    print(f"Průměrný věk: {avg_age}")


if __name__ == "__main__":
    main()