I am a university student. A computer association gave me a computer to use during my studies on the condition that I return it to them after finishing university. Now that I have completed my university studies, when I prepared the computer for return, I found in its bag papers and an amount of (30) dinars. These papers are dated (2015), and I received the computer in (2018), which means (3) years after these papers were placed. Am I entitled to take this amount for myself? Note that the cash is sealed in a paper with a person's name written on it?