Compilare: user.cpp: In function ‘int main()’: user.cpp:77:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < H2.size() && OK; ++ i) ^ user.cpp:53:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.in", "r", stdin); ^ user.cpp:54:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("twosets.out", "w", stdout); ^ user.cpp:56:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i\n", &T); ^ user.cpp:62:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S + 1); ^ user.cpp:66:20: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S + 1); ^ /tmp/cc5xv60w.o: In function `main': user.cpp:(.text.startup+0x8c): warning: the `gets' function is dangerous and should not be used.