Compilare: user.cpp: In function ‘int main()’: user.cpp:31:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!a[i][j]) ^ user.cpp:38:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!a[i][j]) ^ user.cpp:67:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(!a[i][j]) ^