foo.c: In function 'main':
foo.c:5:1: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d",&n);
 ^~~~~~~~~~~~~~
foo.c:7:23: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
 for(int j=1;j<=i;j++) scanf("%d",&a[i][j]);
                       ^~~~~~~~~~~~~~~~~~~~

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