foo.c:15:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~
foo.c: In function 'main':
foo.c:20:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d %d", &m, &n, &k);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:25:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &x[i][j]);
    ^~~~~~~~~~~~~~~~~~~~~

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