Compilare: user.cpp: In function ‘unsigned int fr(int, int, int)’: user.cpp:15:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x<=hatv && y<=hatv) ^ user.cpp:15:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x<=hatv && y<=hatv) ^ user.cpp:19:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x<=hatv && y>hatv) ^ user.cpp:19:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x<=hatv && y>hatv) ^ user.cpp:23:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x>hatv && y>hatv) ^ user.cpp:23:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x>hatv && y>hatv) ^ user.cpp:25:43: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] return fr(k-1, x-hatv, y-hatv)+hatv*hatv<<1; ^ user.cpp:27:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x>hatv && y<=hatv) ^ user.cpp:27:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (x>hatv && y<=hatv) ^ user.cpp:29:47: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] return fr(k-1, hatv-y+1, hatv<<1-x+1)+3*hatv*hatv; ^ user.cpp:33:1: warning: control reaches end of non-void function [-Wreturn-type] } ^