Compilare: user.cpp: In function ‘void solve()’: user.cpp:50: warning: comparison between signed and unsigned integer expressions user.cpp:54: warning: comparison between signed and unsigned integer expressions user.cpp:55: warning: operation on ‘C’ may be undefined user.cpp:57: warning: comparison between signed and unsigned integer expressions user.cpp:58: warning: operation on ‘i’ may be undefined user.cpp:63: warning: comparison between signed and unsigned integer expressions