计算员工偏好订单匹配率

def solve():
    from pyodide.http import open_url
    from io import StringIO
    import pandas as pd
    orders=pd.read_csv(StringIO(open_url(____).read()))
    items=pd.read_csv(StringIO(open_url(____).read()))
    dishes=pd.read_csv(StringIO(open_url(____).read()))
    prefs=pd.read_csv(StringIO(open_url(____).read()))
    merged=orders.merge(____)
    merged=merged.merge(____)
    merged=merged.merge(prefs[['____','____']].rename(____),on='____',how='____')
    veg_orders=merged[merged['____']==____]
    if len(____)>____:
        correct=len(____)
        rate=round(correct/len(____)*____,____)
        print(____)
    else:
        print(____)
    print(____)