/*

 ∧＿∧
( ･ω･｡)つ━☆・*。
⊂　 ノ 　　　・゜
しーＪ　　 Accepted

*/



// #pragma GCC optimize("O3")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll long long
#define all(x) begin(x), end(x)
#define x first
#define y second
#define int long long

using namespace std;
using namespace __gnu_pbds;

typedef long double ld;
template<typename T>
using kawaii_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ld PI = atan2(0, -1);

void seriy() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout << fixed << setprecision(14);
    #ifdef _offline
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif
}

const int MAXN = 1e5 + 10;
const int MAXM = 600;
const int INF = 1e18 + 7;
const int BASE = 47;
const int MOD = 998244353;
const int MAXLOG = 61;
const ld EPS = 1e-8;

ld binpow(ld a, int pw) {
    if(pw == 0) return 1;
    if(pw % 2) {
        return binpow(a, pw - 1) * a;
    }
    else {
        a *= a;
        return binpow(a, pw / 2);
    }
}

signed main() {
    seriy();
    int n;
    ld m, t;
    cin >> n >> m >> t;
    vector<pair<ld, ld>> a(n);
    for(int i = 0; i < n; i++) {
        cin >> a[i].x >> a[i].y;
        a[i].y = (a[i].y / 1e6) + 1;
    }
    sort(all(a), [&](pair<ld, ld> a, pair<ld, ld> b) {
        return a.y < b.y;
    });
    // for(auto i : a) {
    //     cerr << i.x << " " << i.y << '\n';
    // }
    vector<ld> pw(n);
    for(int i = 0; i < n; i++) {
        pw[i] = binpow(a[i].y, m);
    }
    int cnt = 100;
    ld l = 0, r = INF;
    while(cnt--) {
        ld mid = (l + r) / 2.;
        ld need = mid;
        ld sum = 0;
        vector<ld> cnt(n), now(n), start(n);
        for(int i = 0; i < n; i++) {
            ld can = min(need, a[i].x);
            cnt[i] = can;
            start[i] = can;
            need -= can;
        }
        int cur = n - 1;
        for(int i = 0; i < m; i++) {
            ld tt = t;
            while(tt > 0) {
                // cerr << tt << '\n';
                if(abs(cnt[cur] - now[cur]) < EPS) {
                    cur--;
                }
                if(cur < 0) break;
                // cerr << a[cur].y << '\n';
                cnt[cur] = start[cur] * binpow(a[cur].y, i);
                // cerr << cur << '\n';
                // cerr << abs(cnt[cur] - now[cur]) << " " << tt << '\n';
                ld out = min(abs(cnt[cur] - now[cur]), tt);

                now[cur] += out;
                tt -= out;
            }
            if(cur < 0) break;
        }
        if(abs(cnt[0] - now[0]) < EPS) {
            l = mid;
        }
        else {
            r = mid;
        }
    }
    cout << r;
    return 0;
}