foo.c:3:1: warning: return type defaults to 'int' [-Wimplicit-int]
    3 | pd(int n)
      | ^~
foo.c: In function 'main':
foo.c:26:9: warning: unused variable 'j' [-Wunused-variable]
   26 |     int j=0;
      |         ^
foo.c:25:11: warning: unused variable 'i' [-Wunused-variable]
   25 |     int a,i;
      |           ^
foo.c: In function 'pd':
foo.c:20:1: warning: control reaches end of non-void function [-Wreturn-type]
   20 | }
      | ^

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