foo.c: In function 'main':
foo.c:18:14: warning: unused variable 'x' [-Wunused-variable]
     int m, n,x, num[500][500];
              ^
foo.c:21:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &m, &n);
     ^~~~~~~~~~~~~~~~~~~~~
foo.c:26:13: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d", &num[i][j]);
             ^~~~~~~~~~~~~~~~~~~~~~~

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