/in/foo.c:2:1: warning: return type defaults to 'int' [-Wimplicit-int]
 main()
 ^~~~
/in/foo.c: In function 'main':
/in/foo.c:4:22: warning: unused variable 'max' [-Wunused-variable]
   int n,i,a[20],temp,max,k=1;
                      ^~~