#include <bits/stdc++.h>

using namespace std;

typedef long long i64;
const int BUFFER_SIZE = 1 << 20;
char rb[BUFFER_SIZE], *rp = rb, *rt = rb;
inline char read_char() {
    return rp == rt ? (rt = rb + fread(rb, 1, BUFFER_SIZE, stdin), rp = rb, *rp ++) : *rp ++;
}
inline i64 read_int() {
    i64 x = 0;
    char ch = read_char(), flag = 0;
    while (ch != '-' && (ch < '0' || ch > '9')) {
        ch = read_char();
    }
    if (ch == '-') {
        flag = 1;
        ch = read_char();
    }
    for (x = 0; ch >= '0' && ch <= '9'; ch = read_char()) {
        x = x * 10 + (ch - '0');
    }
    return flag ? -x : x;
}


const int MAX_N = 50000 + 5;

int N, K, ans;
i64 S;
int a[MAX_N], b[MAX_N], f[MAX_N];
priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>> qa, qb, qd;

int main() {
    N = read_int(), K = read_int();
    S = read_int();
    for (int i = 1; i <= N; i ++) {
        b[i] = read_int(), a[i] = read_int();
        qa.push(make_pair(a[i], i));
        qb.push(make_pair(b[i], i));
    }
    // printf("[1]\n");
    for (; K && qa.size(); K --) {
        int i = qa.top().second;
        if (S < a[i]) break;
        qa.pop();
        S -= a[i], f[i] = 1, ans ++;
        // printf("f[%d]=%d  S=%lld\n", i, f[i], S);
        qd.push(make_pair(b[i] - a[i], i));
    }
    // printf("[2]\n");
    while (1) {
        for (; qb.size() && f[qb.top().second]; qb.pop());
        int tb = qb.size() ? qb.top().first : -1;
        for (; qa.size() && f[qa.top().second]; qa.pop());
        int tc = qa.size() && qd.size() ? qa.top().first + qd.top().first : -1;
        if (tb != -1 && (tc == -1 || tb <= tc)) {
            if (S < tb) break;
            int i = qb.top().second;
            qb.pop();
            S -= b[i], f[i] = 2, ans ++;
            // printf("f[%d]=%d  S=%lld\n", i, f[i], S);
        } else if (tc != -1 && (tb == -1 || tb > tc)) {
            if (S < tc) break;
            int i = qa.top().second, j = qd.top().second;
            qa.pop(), qd.pop();
            f[j] = 2, f[i] = 1, ans ++;
            S -= a[i] + b[j] - a[j];
            // printf("f[%d]=%d, f[%d]=%d  S=%lld\n", j, f[j], i, f[i], S);
            qd.push(make_pair(b[i] - a[i], i));

        } else break;
    }
    printf("%d\n", ans);
    return 0;
}