foo.c: In function 'main':
foo.c:18:3: warning: statement with no effect [-Wunused-value]
   for(j;j>=i;j--){
   ^~~
foo.c:19:5: warning: statement with no effect [-Wunused-value]
     for(i;i<j;i++){
     ^~~
foo.c:26:3: warning: statement with no effect [-Wunused-value]
   for(i;i<=n;i++){
   ^~~
foo.c:31:3: warning: statement with no effect [-Wunused-value]
   for(i;i>0;i--){
   ^~~
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ^~~~~~~~~~~~~~
foo.c:13:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&x);
     ^~~~~~~~~~~~~~

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