Compilare: user.cpp: In function ‘void Back(int)’: user.cpp:155:21: warning: unused variable ‘s1’ [-Wunused-variable] int s1 = sr[i], s2 = sc[i]; ^ user.cpp:155:33: warning: unused variable ‘s2’ [-Wunused-variable] int s1 = sr[i], s2 = sc[i]; ^ user.cpp: In function ‘void read()’: user.cpp:12:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dame2.in", "r", stdin); ^ user.cpp:17:19: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a[i]); ^ user.cpp: In function ‘void write()’: user.cpp:171:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dame2.out", "w", stdout); ^ In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from /usr/include/i386-linux-gnu/c++/4.8/bits/stdc++.h:46, from user.cpp:1: In function ‘char* gets(char*)’, inlined from ‘void read()’ at user.cpp:17:19: /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/ccp3pNbg.o: In function `read()': user.cpp:(.text+0x50): warning: the `gets' function is dangerous and should not be used.