Compilare: user.cpp: In function ‘long long int solve(int)’: user.cpp:19:20: warning: variable ‘prev’ set but not used [-Wunused-but-set-variable] int spec=0,prev; ^~~~ user.cpp:72:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ~^~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:79:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d%d",&N,&M); ^ user.cpp:83:27: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&X); ^ user.cpp:91:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d%d",&L,&R); ^