cannot open output file a.out: Permission denied, on a simple compilation

I wrote some code in vim and whenever I try to run the code it shows this:

coolmego@coolmego-PC:~/coolmego/cprograms$ gcc dfs8puzz.c 
/usr/bin/ld: cannot open output file a.out: Permission denied
collect2: ld returned 1 exit status
coolmego@coolmego-PC:~/coolmego/cprograms$ ./a.out
bash: ./a.out: No such file or directory

What should I do?