foo.c: In function 'main':
foo.c:10:4: error: expected ')' before ';' token
  (i;i>0;i=i/10);
    ^
foo.c:10:2: warning: statement with no effect [-Wunused-value]
  (i;i>0;i=i/10);
  ^
foo.c:9:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&num);
  ^~~~~~~~~~~~~~~~

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