var toInt = x=>parseInt(x,10);
var toIntArr = arr=>arr.map(x=>toInt(x));
var abs = x=>x>0?x:-x;
function min(){var rest = arguments,val=rest[0];for(var i=1;i<rest.length;i++)if(rest[i]<val)val = rest[i];return val}
function max(){var rest = arguments,val=rest[0];for(var i=1;i<rest.length;i++)if(rest[i]>val)val = rest[i];return val}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));
 
function Main(input){
	var input = input.split('\n');
	//input = input.map(e => toIntArr(e.split(' ')));
	var s = input[0].split('').map(el=>el==='B'?1:0);
	var l = s.length;
	var ans = 0;
	var num = 0;
	for(var i = 0; i<l ;i++){
		if(s[l-i-1]){
			ans += i - num;
			num++;
		}
	}

	console.log(ans);
}