Compilare: user.cpp: In function ‘void get_prefix()’: user.cpp:22: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void print_prefix()’: user.cpp:50: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void solve()’: user.cpp:61: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:78: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result