Compilare: user.cpp: In function ‘void del(int, int, int)’: user.cpp:20:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[b].size();++i) ^ user.cpp: In function ‘void euler(int)’: user.cpp:64:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sol.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:71:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in", "r", stdin); ^ user.cpp:72:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.out", "w", stdout); ^ user.cpp:74:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &n); ^ user.cpp:77:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &a, &b); ^