[Solved] Exec-display wrong number(255)

Hello! I am a beginner and I have a problem with the exec exit command. I want to display a number that is given by an executable file (.out).

Number Last_price "The cost  is [%.1f £]" <pound> {channel="exec:command:apc:exit"}


Thing exec:command:apc [command="/var/lib/openhab2/price.out"]


Text item=Last_price 

The code shows correct values, when the Last_price has specific values. But when the Last_price is >255 the displayed value is wrong.
Does someone know something about this?

Edit: I solved it. I made Last_price a string and the problem is solved.