/in/foo.c:3:1: error: expected identifier or '(' before 'for'
    3 | for(int i=0;i<n;i++){
      | ^~~
/in/foo.c:3:14: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
    3 | for(int i=0;i<n;i++){
      |              ^
/in/foo.c:3:18: error: expected '=', ',', ';', 'asm' or '__attribute__' before '++' token
    3 | for(int i=0;i<n;i++){
      |                  ^~
/in/foo.c: In function 'main':
/in/foo.c:19:21: error: invalid use of void expression
   19 |         printf("%d",fun(a,n));
      |                     ^~~~~~~~