读取第一行

with open("est.txt","r",encoding="utf-8") as f:
    r = f.readlines()
    print(r[0])  # 读第一行

读取最后一行

with open("est.txt","r",encoding="utf-8") as f:
    r = f.readlines()
    print(r[0])  # 读第一行
    print(r[-1])  # 读最后一行