#include using namespace std; typedef long long ll; typedef pair P; #define REP(i,n) for(ll i=0;i> N; vector a(N+1,0); for(i=1;i> X; if(X==1){ a[i]=X; } else if(X==-1) return 0; } vector u(N+1,0); ll s=0; for(i=1;i