Basic programs

1. GCD.c
2. avg.java
3. avg_of_3.c
4. check_triag.c
5. even_till_n.c
6. fact.c
7. fib.c
8. n3_plus2_mod_4.java
9. positive.c
10. primalty.c
11. prime_till_n.java
12. size.java
13. sum_prod_till_n.java
14. test.java
15. valid_triag.c