Compilare: user.cpp: In function 'int main()': user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void solve()': user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp:48: warning: comparison between signed and unsigned integer expressions user.cpp:61: warning: comparison between signed and unsigned integer expressions user.cpp:66: warning: comparison between signed and unsigned integer expressions user.cpp:42: warning: unused variable 'j' user.cpp: In function 'void read_in()': user.cpp:100: warning: comparison between signed and unsigned integer expressions