Compilare: user.cpp: In function ‘void bktr(int)’: user.cpp:18:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sol.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:38:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^