Compilare: user.cpp: In function ‘void comb(int, int)’: user.cpp:25:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[b].size();i++) ^ user.cpp:36:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[b].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:61:11: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(k==2) ^