Compilare: main.cpp: In function 'void FFT(std::vector<std::complex<double> >, std::vector<std::complex<double> >&, bool)': main.cpp:26:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::complex<double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | for (int index = 0; index < vec.size();) { | ~~~~~~^~~~~~~~~~~~ main.cpp:37:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::complex<double> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 37 | for (int index = 0; index < vec.size() >> 1; index++) { | ~~~~~~^~~~~~~~~~~~~~~~~ main.cpp: In function 'void Multiply(const std::vector<long long int>&, const std::vector<long long int>&, std::vector<long long int>&)': main.cpp:51:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | for (tot_size = 1; tot_size < vec0.size() || tot_size < vec1.size(); tot_size <<= 1); | ~~~~~~~~~^~~~~~~~~~~~~ main.cpp:51:56: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 51 | for (tot_size = 1; tot_size < vec0.size() || tot_size < vec1.size(); tot_size <<= 1); | ~~~~~~~~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:92:22: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 92 | if (vec[0].size() <= nri) { | ~~~~~~~~~~~~~~^~~~~~ main.cpp:101:22: warning: comparison of integer expressions of different signedness: 'std::vector<long long int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 101 | if (vec[1].size() <= nri) { | ~~~~~~~~~~~~~~^~~~~~ main.cpp:110:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 110 | for (int index = 0; index < ans.size(); index++) { | ~~~~~~^~~~~~~~~~~~