Compilare: user.cpp: In function ‘bool possible(int)’: user.cpp:60:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] REP(j, 2, tmp[0]) ^ user.cpp:20:42: note: in definition of macro ‘REP’ #define REP(i, a, b) for(int i = a; i <= b; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:78:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("subsecvente2.in", "r", stdin); ^ user.cpp:79:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("subsecvente2.out", "w", stdout); ^ user.cpp:87:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &N); ^ user.cpp:90:27: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(x[i] + 1); ^ In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from /usr/include/c++/4.8/ext/string_conversions.h:43, from /usr/include/c++/4.8/bits/basic_string.h:2815, from /usr/include/c++/4.8/string:52, from /usr/include/c++/4.8/stdexcept:39, from /usr/include/c++/4.8/array:38, from /usr/include/c++/4.8/tuple:39, from /usr/include/c++/4.8/bits/stl_map.h:63, from /usr/include/c++/4.8/map:61, from user.cpp:3: In function ‘char* gets(char*)’, inlined from ‘int main()’ at user.cpp:90:27: /usr/include/i386-linux-gnu/bits/stdio2.h:230:28: warning: call to ‘__gets_warn’ declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size [enabled by default] return __gets_warn (__str); ^ /tmp/ccCqQaIj.o: In function `main': user.cpp:(.text.startup+0xca): warning: the `gets' function is dangerous and should not be used.