Compilare: user.cpp: In function ‘void read()’: user.cpp:12: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp:13: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve()’: user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:49: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result In file included from /usr/include/stdio.h:910, from /usr/include/c++/4.4/cstdio:45, from user.cpp:1: In function ‘char* gets(char*)’, inlined from ‘void read()’ at user.cpp:16: /usr/include/bits/stdio2.h:230: warning: call to ‘__gets_warn’ declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size /tmp/cc0Z8qOU.o: In function `read()': user.cpp:(.text+0x265): warning: the `gets' function is dangerous and should not be used. user.cpp:(.text+0x1e6): warning: the `gets' function is dangerous and should not be used.