Compilare: user.cpp: In function ‘int get_number(std::string)’: user.cpp:21:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<n.size();++i) ^ user.cpp: In function ‘void write(std::string)’: user.cpp:29:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<str.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:46:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<q.size();) ^ user.cpp:86:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<u.size();) ^ user.cpp:114:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=1,printf("%d\n",totime);i<sol.size();++i) ^ user.cpp:35:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reteta2.in","r",stdin); ^ user.cpp:36:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reteta2.out","w",stdout); ^ user.cpp:38:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(str); ^ /tmp/ccCxsW7s.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.