Compilare: user.cpp: In function ‘void Add(std::vector<int>&, std::vector<int>&)’: user.cpp:17:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = a.size() + 1; i <= b.size(); i++) { ^ user.cpp:22:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = b.size() + 1; i <= a.size(); i++) { ^ user.cpp:27:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < a.size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:39:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm6.in", "r", stdin); ^ user.cpp:40:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm6.out", "w", stdout); ^ user.cpp:42:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &K); ^