Compilare: user.cpp: In function ‘int main()’: user.cpp:116:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("barbar.in", "r", stdin); ^ user.cpp:117:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("barbar.out", "w", stdout); ^ user.cpp:120:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d ",&n,&m); ^ user.cpp:122:24: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(mx[i] + 1); ^ user.cpp: In function ‘void lazy_deletion(int&)’: user.cpp:111:22: warning: ‘now.PII::y’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(now.x!=dest.x || now.y!=dest.y) ^ user.cpp:111:5: warning: ‘now.PII::x’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(now.x!=dest.x || now.y!=dest.y) ^ user.cpp:84:28: warning: ‘beg.PII::y’ may be used uninitialized in this function [-Wmaybe-uninitialized] bn[beg.x][beg.y] = true; ^ user.cpp:84:28: warning: ‘beg.PII::x’ may be used uninitialized in this function [-Wmaybe-uninitialized] user.cpp:111:5: warning: ‘dest.PII::x’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(now.x!=dest.x || now.y!=dest.y) ^ user.cpp:111:22: warning: ‘dest.PII::y’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(now.x!=dest.x || now.y!=dest.y) ^ 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:2: In function ‘char* gets(char*)’, inlined from ‘int main()’ at user.cpp:122:24: /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/ccfuO9xi.o: In function `main': user.cpp:(.text.startup+0x85): warning: the `gets' function is dangerous and should not be used.