#includeusing namespace std;double power(int x,int y){ if(y==0)return 1;else return x*power(x,y-1);}int main(){int a,b;cin>>a;cin>>b;cout<}
double power(int x,int y){ if(y=0)return 1;else return power(x,y-1)*x;}
Power 换成fac也行