Compilare: user.cpp: In function ‘void FFT(std::vector<std::complex<double> >&, double)’: user.cpp:23:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<V.size();i++) ~^~~~~~~~~ user.cpp:35:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<V.size()/2;k++) ~^~~~~~~~~~~ user.cpp:43:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<V.size();i++) ~^~~~~~~~~ user.cpp: In function ‘std::vector<int> Multiply(std::vector<int>, std::vector<int>)’: user.cpp:51:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(S<a.size()+b.size()) ~^~~~~~~~~~~~~~~~~~ user.cpp:54:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();i++) ~^~~~~~~~~ user.cpp:58:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b.size();i++) ~^~~~~~~~~ user.cpp: In function ‘void Solve()’: user.cpp:105:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<P.size();i++) ~^~~~~~~~~ user.cpp:82:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&N); ^ user.cpp:87:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&aux); ^ user.cpp:93:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&M); ^ user.cpp:98:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&aux); ^ user.cpp: In function ‘int main()’: user.cpp:113:23: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(IN,"%d",&T); ^