Compilare: user.cpp: In function 'int main()': user.cpp:24: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void solve()': user.cpp:39: warning: comparison between signed and unsigned integer expressions user.cpp:41: warning: comparison between signed and unsigned integer expressions user.cpp:55: warning: comparison between signed and unsigned integer expressions user.cpp:60: warning: comparison between signed and unsigned integer expressions user.cpp:36: warning: unused variable 'j' user.cpp: In function 'void read_in()': user.cpp:94: warning: comparison between signed and unsigned integer expressions