Compilare: user.cpp: In function ‘void do_magic()’: user.cpp:89:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v.size();++i) { ^ user.cpp:90:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<w[i].size();++j) { ^ user.cpp: In function ‘int main()’: user.cpp:98:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "ahocorasick.in","r",stdin ); ^ user.cpp:99:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "ahocorasik.out","w",stdout ); ^ user.cpp:100:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s%d",s,&N); ^ user.cpp:103:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s",t); ^