#include<iostream>
#include<string>
#include<algorithm>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
int ft[1000001];
int read_price(void) {
    double f;
    scanf("%lf",&f);
    return (int)((f+1e-9)*100.0);
}
void update(int index, int value){
	while(index<1000001){
		ft[index] += value;
		index += index&-index;
	}
}
long long sumValue(int index){
	long long sum = 0;
	while(index > 0){
		sum += ft[index];
		index -= index&-index;
	}
	return sum;
}
main(){
	for(int i=0; i<1000001; i++)
		ft[i] = 0;
	char sityva[6];
	long long answer = 0;
	double money;
	while(true){
		scanf("%s",&sityva);
		if(sityva[0] == 'Q')
			break;

		int posMoney = read_price();
		if(sityva[0] == 'B'){
			update(posMoney,1);
		}else if(sityva[0] == 'D'){
			update(posMoney,-1);
		}else if(sityva[0] == 'S'){
			int quantity;
			cin>>quantity;

			long long n;
			n = sumValue(1000000)-sumValue(posMoney-1);

			if(quantity<n)
				n = quantity;
			answer += n;
		}
	}
	double ans = 0;
	long long a = answer/100;
	long long b = answer%100;

	for(int i=0; i<a; i++){
		ans += 1;
	}
	for(int i=0; i<b; i++){
		ans += 0.01;
	}
	printf("%lf",ans);
}