foo.c: In function 'main':
foo.c:6:18: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  int m, n, i, j; scanf("%d%d", &m, &n);
                  ^~~~~~~~~~~~~~~~~~~~~
foo.c:7:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &a[0][0]);
  ^~~~~~~~~~~~~~~~~~~~~
foo.c:11:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[0][j]);
   ^~~~~~~~~~~~~~~~~~~~~
foo.c:19:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &a[i][0]);
   ^~~~~~~~~~~~~~~~~~~~~
foo.c:23:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &a[i][j]);
    ^~~~~~~~~~~~~~~~~~~~~

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