foo.cc: In function 'int main()':
foo.cc:9:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:11:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |   for(int j=1;j<=i;j++) scanf("%d",&a[i][j]);
      |                         ~~~~~^~~~~~~~~~~~~~~

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