Compilare: main.cpp: In function 'int main()': main.cpp:22:99: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("lgput.in","r",stdin),freopen("lgput.out","w",stdout),fread(r,1,100,stdin),x=A(),p=A(); ^ main.cpp:22:99: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] main.cpp:22:99: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from main.cpp:1: In function 'size_t fread(void*, size_t, size_t, FILE*)', inlined from 'int main()' at main.cpp:22:99: /usr/include/x86_64-linux-gnu/bits/stdio2.h:293:71: warning: call to '__fread_chk_warn' declared with attribute warning: fread called with bigger size * nmemb than length of destination buffer return __fread_chk_warn (__ptr, __bos0 (__ptr), __size, __n, __stream); ^