Compilare: user.cpp: In function ‘int op3(int)’: user.cpp:8:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<H[rest].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:39:3: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(op==3) ^ user.cpp: In function ‘int op1(int)’: user.cpp:18:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int op2(int)’: user.cpp:26:1: warning: control reaches end of non-void function [-Wreturn-type] } ^