The best option may be to get a one way cat door - let them out but not back in. My father does this with his cats, and it works very well. The cats have learned to sit on the kithen windowsill when they want to come back in, and they have several sheltered places to wait outside if nobody's home.
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Overhead, the Albatross hangs motionless upon the air,
And deep beneath the rolling waves,
In labyrinths of Coral Caves,
The Echo of a distant time
Comes willowing across the sand;
And everthing is Green and Submarine
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