Compilare: user.cpp: In function 'void debug()': user.cpp:37: warning: comparison between signed and unsigned integer expressions user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void build()': user.cpp:58: warning: comparison between signed and unsigned integer expressions user.cpp:58: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void solve()': user.cpp:112: warning: comparison between signed and unsigned integer expressions user.cpp:115: warning: comparison between signed and unsigned integer expressions user.cpp:123: warning: comparison between signed and unsigned integer expressions user.cpp:126: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void write_data()': user.cpp:145: warning: comparison between signed and unsigned integer expressions