Compilare: user.cpp: In function ‘int main()’: user.cpp:22:26: warning: operation on ‘k’ may be undefined [-Wsequence-point] st[++k]=a[st[k-1]][j]; ^ In file included from /usr/include/string.h:642:0, from /usr/include/c++/4.8/cstring:42, from user.cpp:2: In function ‘void* memcpy(void*, const void*, size_t)’, inlined from ‘int main()’ at user.cpp:37:28: /usr/include/i386-linux-gnu/bits/string3.h:52:71: warning: call to void* __builtin___memcpy_chk(void*, const void*, unsigned int, unsigned int) will always overflow destination buffer [enabled by default] return __builtin___memcpy_chk (__dest, __src, __len, __bos0 (__dest)); ^