Compilare: user.c: In function ‘flip_col’: user.c:54:9: warning: unused variable ‘i’ [-Wunused-variable] int i, j; ^ user.c: In function ‘main’: user.c:65:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d%d", &n, &m); ^ user.c:70:19: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &t[i][j]); ^