Compilare: user.cpp: In function ‘void Cross()’: user.cpp:65:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < V[nod].size(); ++i) ^ user.cpp:78:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i <f.size(); ++i) ^ user.cpp:81:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < V[f[i]].size(); ++j) ^ user.cpp:89:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < s.size(); ++j) ^ In file included from /usr/include/string.h:642:0, from /usr/include/c++/4.8/cstring:42, from user.cpp:4: In function ‘void* memset(void*, int, size_t)’, inlined from ‘int main()’ at user.cpp:32:39: /usr/include/i386-linux-gnu/bits/string3.h:85:70: warning: call to void* __builtin___memset_chk(void*, int, unsigned int, unsigned int) will always overflow destination buffer [enabled by default] return __builtin___memset_chk (__dest, __ch, __len, __bos0 (__dest)); ^