Compilare: user.cpp: In function ‘void back(int)’: user.cpp:28:7: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!ok) ^ user.cpp: In function ‘int main()’: user.cpp:71:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(inf,"r",stdin); ^ user.cpp:72:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outf,"w",stdout); ^ user.cpp:73:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&n,&m,&nr); ^ user.cpp:77:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^