Compilare: user.cpp: In function ‘int main()’: user.cpp:15:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rj.in","r",stdin); ^ user.cpp:16:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rj.out","w",stdout); ^ user.cpp:18:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n",&n,&m); ^ user.cpp:21:28: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(v,1000,stdin); ^ user.cpp:53:22: warning: ‘J2’ may be used uninitialized in this function [-Wmaybe-uninitialized] pas.x=J1;pas.y=J2; ^ user.cpp:53:13: warning: ‘J1’ may be used uninitialized in this function [-Wmaybe-uninitialized] pas.x=J1;pas.y=J2; ^ user.cpp:32:16: warning: ‘R2’ may be used uninitialized in this function [-Wmaybe-uninitialized] R[R1][R2]=1; ^ user.cpp:32:16: warning: ‘R1’ may be used uninitialized in this function [-Wmaybe-uninitialized] In file included from /usr/include/stdio.h:934:0, from /usr/include/c++/4.8/cstdio:42, from user.cpp:1: In function ‘char* fgets(char*, int, FILE*)’, inlined from ‘int main()’ at user.cpp:21:28: /usr/include/i386-linux-gnu/bits/stdio2.h:253:58: warning: call to ‘__fgets_chk_warn’ declared with attribute warning: fgets called with bigger size than length of destination buffer [enabled by default] return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^