Compilare: user.cpp: In function ‘int main()’: user.cpp:49:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 1; i < l.size(); i++){ ^ user.cpp:55:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 1; i < l.size(); i++) ^ user.cpp:22:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm2.in", "r", stdin); ^ user.cpp:23:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm2.out", "w", stdout); ^ user.cpp:24:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:26:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i]); ^