Compilare: user.cpp: In function ‘int col_cost(int, int, int, int)’: user.cpp:39:12: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!( (x1<=j && j<=x2) || (x3<=j && j<=x4) ) ) ^ user.cpp: In function ‘void read()’: user.cpp:13:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&n,&m); ^ user.cpp:15:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n",a[i]+1); ^ user.cpp: In function ‘int main()’: user.cpp:78:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hashtag.in","r",stdin); ^ user.cpp:79:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hashtag.out","w",stdout); ^