Compilare: user.cpp: In function 'int main()': user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void solve()': user.cpp:43: warning: comparison between signed and unsigned integer expressions user.cpp:46: warning: comparison between signed and unsigned integer expressions user.cpp:59: warning: comparison between signed and unsigned integer expressions user.cpp:64: warning: comparison between signed and unsigned integer expressions user.cpp:40: warning: unused variable 'j' user.cpp: In function 'void read_in()': user.cpp:97: warning: comparison between signed and unsigned integer expressions