foo.c: In function 'main':
foo.c:42:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &R, &C);
     ^~~~~~~~~~~~~~~~~~~~~~
foo.c:45:13: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d", &a[i][j]);
             ^~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务