Compilare: user.cpp: In function ‘int main()’: user.cpp:52:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<a.size();i++) { ^ user.cpp:56:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<a.size();j++) { ^ user.cpp:29:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gap.in","r",stdin); ^ user.cpp:30:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gap.out","w",stdout); ^ user.cpp:36:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&T); ^ user.cpp:40:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&x); ^