Compilare: user.c: In function ‘start’: user.c:58:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘main’: user.c:66:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d", &n, &m); ^ user.c:69:12: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d", &flip[i][j]); ^