Compilare: user.c: In function ‘calc_max_sum’: user.c:59:13: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] cur_sum += abs(col_sum); ^ user.c: In function ‘read_data’: user.c:9:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d", &N, &M); ^ user.c:14:19: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d", &grid[i][j]); ^