#include <iostream>
#include <vector>
#include <map>
#include <tuple>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define eb emplace_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
int getInt(){int x;scanf("%d",&x);return x;}
template<typename T>istream& operator>>(istream&i,v(T)&v){rep(j,sz(v))i>>v[j];return i;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v){return i>>v.fi>>v.se;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,const pair<T1,T2>&v){return o<<v.fi<<","<<v.se;}
template<typename T>bool mins(T& x,const T&y){if(x>y){x=y;return true;}else return false;}
template<typename T>bool maxs(T& x,const T&y){if(x<y){x=y;return true;}else return false;}
template<typename T>ll suma(const v(T)&a){ll res(0);for(auto&&x:a)res+=x;return res;}
const double eps = 1e-10;


int main() {
    ll n, x, v, p;
    scanf("%lld", &n);
    scanf("%lld", &x);

    ll sum = 0;
    int result = -1;
    for(int i=0; i<n; i++) {
        scanf("%lld", &v);
        scanf("%lld", &p);
        sum += v * p;
        if(float(sum) / float(100) > x) {
            result = i+1;
            break;
        }
    }


    cout << result << '\n';
    return 0;

}
#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define FastIO ios_base::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL)
typedef long long ll;
int main(){
  FastIO;

  ll n,x;
  cin>>n;
  int c=0;
  string s,s1,sf;
  for(ll i=1;i<=1000000;i++){
    s=to_string(i);
    s1=to_string(i);
    sf=s+s1;
    stringstream str(sf);
    str>>x;
    if(x<=n){
      c++;
    }
  }
  std::cout << c << '\n';
  return 0;
}
