// Skyqwq
#include <bits/stdc++.h>

#define pb push_back
#define fi first
#define se second
#define mp make_pair

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

template <typename T> bool chkMax(T &x, T y) { return (y > x) ? x = y, 1 : 0; }
template <typename T> bool chkMin(T &x, T y) { return (y < x) ? x = y, 1 : 0; }

template <typename T> void inline read(T &x) {
    int f = 1; x = 0; char s = getchar();
    while (s < '0' || s > '9') { if (s == '-') f = -1; s = getchar(); }
    while (s <= '9' && s >= '0') x = x * 10 + (s ^ 48), s = getchar();
    x *= f;
}

const int N = 2e5 + 5;

int n, m;

double p[N], q[N];

char ty[4], op[N];

int st[N];

set<int> s;

struct Mat{
	double w[2][2];
	Mat operator * (const Mat &b) const {
		Mat c; 
		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < 2; j++) {
				c.w[i][j] = 0;
				for (int k = 0; k < 2; k++)
					c.w[i][j] += w[i][k] * b.w[k][j];
			}
		}
		return c;
	}
	Mat operator + (const Mat &b) const {
		Mat c; 
		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < 2; j++) {
				c.w[i][j] = w[i][j] + b.w[i][j];
			}
		}
		return c;
	}
} A[N];

struct Node{
	Mat s, v;
} t[N << 2];

Node inline merge(const Node &x, const Node &y, Mat w) {
	return (Node) { x.s * w * y.s, (x.s * w * y.v) + (x.v * w * y.s) };
}

double ans;

#define ls (p << 1)
#define rs (p << 1 | 1)

void build(int p, int l, int r) {
	if (l == r) {
		t[p].s.w[0][0] = t[p].s.w[1][1] = t[p].v.w[1][1] = 1;
		return;
	}
	int mid = (l + r) >> 1;
	build(ls, l, mid);
	build(rs, mid + 1, r);
	t[p] = merge(t[ls], t[rs], A[mid + 1]);
}

Node query(int p, int l, int r, int x, int y) {
	if (x <= l && r <= y) return t[p];
	int mid = (l + r) >> 1;
	if (y <= mid) return query(ls, l, mid, x, y);
	if (x > mid) return query(rs, mid + 1, r, x, y);
	return merge(query(ls, l, mid, x, y), query(rs, mid + 1, r, x, y), A[mid + 1]);
}

double calc(int l, int r) {
	if (l + 1 == r) return 0;
	Node u = query(1, 0, n + 1, l, r);
	double z = u.s.w[st[l]][st[r]];
	double sum = u.v.w[st[l]][st[r]] - (st[l] + st[r]) * z;
	return sum / z;
}

void inline ins(int x, int c) {
	auto o = s.lower_bound(x);
	int R = *o;
	--o;
	int L = *o;
	s.insert(x);
	ans -= calc(L, R);
	st[x] = c;
	ans += calc(L, x);
	ans += calc(x, R);
	ans += st[x];
}

void inline del(int x) {
	ans -= st[x];
	s.erase(x);
	auto o = s.lower_bound(x);
	int R = *o;
	--o;
	int L = *o;
	ans -= calc(L, x);
	ans -= calc(x, R);
	st[x] = -1;
	ans += calc(L, R);
}

int main() {
	memset(st, -1, sizeof st);
	read(n), read(m); scanf("%s", ty);
	st[0] = st[n + 1] = 1;
	for (int i = 1; i <= n; i++) {
		scanf("%lf", p + i);
		if (i != 1) scanf("%lf", q + i);
	}
	p[n + 1] = q[n + 1] = 1;
	for (int i = 1; i <= n + 1; i++) {
		A[i].w[1][1] = p[i];
		A[i].w[1][0] = (1 - p[i]);
		A[i].w[0][1] = q[i];
		A[i].w[0][0] = (1 - q[i]);
	}
	s.insert(0), s.insert(n + 1);
	build(1, 0, n + 1);
	ans += calc(0, n + 1);
	while (m--) {
		int x; 
		scanf("%s", op); read(x);
		if (op[0] == 'a') {
			int c; read(c);
			ins(x, c);
		} else {
			del(x);
		}
		printf("%.6lf\n", ans);
	}
    return 0;
}