Compilare: user.cpp: In function ‘void back(int, std::vector<std::vector<int> >&, std::vector<int>&, std::vector<bool>&, int, std::vector<int>&)’: user.cpp:9:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pas == a.size()) ^ user.cpp: In function ‘int main()’: user.cpp:37:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numerologie.in", "r", stdin); ^ user.cpp:38:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("numerologie.out", "w", stdout); ^ user.cpp:42:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d" , &n , &m); ^ user.cpp:44:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 0; i < n ; ++i) scanf("%d", &a[i]); ^ user.cpp:45:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 1 ; i <= m ; ++i) scanf("%d", &b[i]); ^