Compilare: user.c: In function ‘main’: user.c:18:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d", &n, &m); ^ user.c:27:4: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &mat[i][j]); ^ user.c:42:36: warning: ‘b’ may be used uninitialized in this function [-Wmaybe-uninitialized] } else if (mat[i][j] - prev != b - a) { ^