Compilare: main.cpp: In function 'std::vector<fft::Complex> fft::fft(const std::vector<int>&, int)': main.cpp:118:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 118 | while (n < v.size()) n <<= 1; | ~~^~~~~~~~~~ In file included from /usr/include/c++/10/cassert:44, from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33, from main.cpp:1: main.cpp:120:21: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 120 | assert(v.size() <= n); | ~~~~~~~~~^~~~ main.cpp:122:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 122 | for (int i = 0; i < v.size(); ++i) | ~~^~~~~~~~~~ main.cpp: In function 'std::vector<long long int> fft::fft(const std::vector<fft::Complex>&)': main.cpp:131:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<fft::Complex>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 131 | for (int i = 0; i < v.size(); ++i) | ~~^~~~~~~~~~ main.cpp:135:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 135 | for (int i = 0; i < result.size(); ++i) | ~~^~~~~~~~~~~~~~~ main.cpp: In function 'std::vector<long long int> fft::multiply(const std::vector<int>&, const std::vector<int>&)': main.cpp:143:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 143 | while (n < a.size() + b.size() - 1) n <<= 1; | ~~^~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:147:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 147 | for (int i = 0; i < a.size(); ++i) | ~~^~~~~~~~~~ main.cpp:149:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 149 | for (int i = 0; i < b.size(); ++i) | ~~^~~~~~~~~~ main.cpp:172:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 172 | for (int i = 0; i < result.size(); ++i) | ~~^~~~~~~~~~~~~~~ main.cpp: In function 'std::vector<int> fft::multiply_mod(const std::vector<int>&, const std::vector<int>&, int)': main.cpp:180:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 180 | while (n < a.size() + b.size() - 1) n <<= 1; | ~~^~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:183:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 183 | for (int i = 0; i < a.size(); ++i) { | ~~^~~~~~~~~~ main.cpp:188:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 188 | for (int i = 0; i < b.size(); ++i) { | ~~^~~~~~~~~~ main.cpp:220:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 220 | for (int i = 0; i < result.size(); ++i) { | ~~^~~~~~~~~~~~~~~