foo.c: In function 'main':
foo.c:8:11: error: 'o' undeclared (first use in this function)
    8 |         x=o;
      |           ^
foo.c:8:11: note: each undeclared identifier is reported only once for each function it appears in
foo.c:9:24: error: expected ';' before ')' token
    9 |         while (x>0){n++)
      |                        ^
      |                        ;
foo.c:9:24: error: expected statement before ')' token

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