long long read(){
	long long ans=0,f=1;
	char ch=getchar();
	while(!isdigit(ch)){
		f*=(ch=='-')?-1:1;
		ch=getchar();
	}
	while(isdigit(ch)){
		ans=ans*10+ch-'0';
		ch=getchar();
	}
	return ans*f;
}