Compilare: main.cpp: In member function 'void Matrix::operator*=(const Matrix&)': main.cpp:47:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < a.size(); i++) ~~^~~~~~~~~~ main.cpp:48:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < aux.a[0].size(); j++) ~~^~~~~~~~~~~~~~~~~ main.cpp:49:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 1; k < a[0].size(); k++) ~~^~~~~~~~~~~~~ main.cpp: In member function 'void Matrix::Print()': main.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < a.size(); i++, cerr << '\n') ~~^~~~~~~~~~ main.cpp:57:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1; j < a[i].size(); j++) ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:77:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("kfib.in", "r", stdin); ^ main.cpp:78:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("kfib.out", "w", stdout); ^ main.cpp:80:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^