Compilare: main.c: In function 'main': main.c:22:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("snake.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:23:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("snake.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:25:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &l); ^~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:30:13: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &mat[i][j]); ^~~~~~~~~~~~~~~~~~~~~~~