foo.c: In function 'main':
foo.c:14:11: error: 'c' undeclared (first use in this function)
   14 |     while(c!=0)
      |           ^
foo.c:14:11: note: each undeclared identifier is reported only once for each function it appears in
foo.c:5:8: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    5 |        scanf("%d%d",&i,&j);
      |        ^~~~~~~~~~~~~~~~~~~

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