Compilare: user.cpp: In function ‘void backtr(int)’: user.cpp:28:11: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(valid(p)) ^ user.cpp: In function ‘int main()’: user.cpp:36:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d%d",&n,&k); ^