Compilare: user.cpp: In function ‘int dimension()’: user.cpp:43:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < l) ^ user.cpp:68:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i*i < n) ^ user.cpp: In function ‘void MATRIX(int, int, int, int)’: user.cpp:76:8: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (x1 <= x2 && y1 <= y2) ^ user.cpp:75:15: warning: unused variable ‘nr’ [-Wunused-variable] int x, y, nr; ^