垦田计划。

垦田计划

二分模板

typedef long long ll;
typedef unsigned long long ull;
#define all(x) (x).begin(),(x).end()
typedef pair<int,int> PII;

int lowbit(ll x) { return x & (- x); }
int gcd(ll a,ll b) { return b ? gcd(b,a % b) : a; }
const int mod = 1e9+7;
int n, m, k; 
const int N = 100010;
int a[N], w[N];

bool check(int as) {
    int now = m;
    for (int i = 1; i <= n; i ++ ) {
        if(a[i] <= as)   continue;
        else {
            int need = a[i] - as;
            need *= w[i];
            now -= need;
        }
    }
    return now >= 0;
}

signed main(){
    IOS;
    cin >> n >> m >> k;
    for (int i = 1; i <= n; i ++ ) cin >> a[i] >> w[i];
    int l = k, r = 1e9;
    while(l < r) {
        int mid = l + r >> 1;
        if(check(mid))  r = mid;
        else l = mid + 1;
    }
    cout << l << endl;
    
    return 0;
}