Compilare: user.cpp: In function ‘int main()’: user.cpp:18: warning: comparison between signed and unsigned integer expressions user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp:51: warning: suggest explicit braces to avoid ambiguous ‘else’ user.cpp:12: warning: ‘s21’ may be used uninitialized in this function user.cpp:12: warning: ‘s22’ may be used uninitialized in this function