foo.c:2:1: warning: return type defaults to 'int' [-Wimplicit-int]
    2 | Sf(int a[500][500],int m,int n)
      | ^~
foo.c: In function 'main':
foo.c:23:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   23 |  scanf("%d %d\n",&m,&n);
      |  ^~~~~~~~~~~~~~~~~~~~~~
foo.c:27:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   27 |    scanf("%d",&a[i][j]);
      |    ^~~~~~~~~~~~~~~~~~~~

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