Compilare: user.cpp: In function ‘void permute()’: user.cpp:13:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (permutation.size() == n) { ^ user.cpp: In function ‘int main()’: user.cpp:34:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.in", "r", stdin); ^ user.cpp:35:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.out", "w", stdout); ^ user.cpp:37:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &n); ^