Compilare: user.cpp: In function ‘void solve()’: user.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a[x].size();i++) ~^~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:53:13: warning: unused variable ‘K’ [-Wunused-variable] int n,m,K,i,x,s,xc; ^ user.cpp:53:19: warning: unused variable ‘s’ [-Wunused-variable] int n,m,K,i,x,s,xc; ^ user.cpp:53:21: warning: unused variable ‘xc’ [-Wunused-variable] int n,m,K,i,x,s,xc; ^~