#include <bits/stdc++.h>
#include <regex>
#ifdef _DEBUG
#include "debug.h"
#endif
#define int ll
#define FOR(i, s, e) for (int i = int(s); i < int(e); ++i)
#define REP(i, e) FOR(i, 0, e)
#define all(v) (v).begin(),(v).end()
#define mkpr make_pair
#define mktp make_tuple
#define tv(tp, i) get<(i)>(tp)
#define CLEAR(obj) obj = decltype(obj)()
#define var auto
#define OUT(type) type &
#define IN(type) const type &
#define self (*this)
#define in :
#define True true
#define False false
using namespace std; using int32 = int32_t; using str = string; using cstr = const str;
using ll = long long; using ull = unsigned long long; using cint = const int; using cll = const ll;
using vi = vector<int>; using vvi = vector<vi>; using vl = vector<ll>; using vvl = vector<vl>;
using vb = vector<bool>; using vvb = vector<vb>; using vd = vector<double>; using vvd = vector<vd>;
using vc = vector<char>; using vvc = vector<vc>; using vs = vector<string>;
using pii = pair<int, int>; using pll = pair<ll, ll>; using pdd = pair<double, double>; using psl = pair<string, ll>;
using tiii = tuple<int, int, int>; using tlll = tuple<ll, ll, ll>;
static const int MGN = 10; static const int ARYSZ_MAX = (int)1e7;
static const ll LINF = LLONG_MAX/2;
#ifdef int
static const int INF = LINF;
#else
static const int INF = INT_MAX/2;
#endif
static double EPS = 1e-9;
#define FASTCIN() cin.tie(0);ios::sync_with_stdio(false);
#ifdef IMPORT_SAMPLE
#define DEBUG_IMPORT(file) vs args(argv, argv+argc);str sample = make_sample(args, file);ifstream ifs(sample); cin.rdbuf(ifs.rdbuf());
#else
#define DEBUG_IMPORT(file)
#endif
static inline bool DBLEQ(double a, double b) {return abs(a - b) < EPS;}
static inline void EPR(str msg) {cerr << msg << endl;}
static inline void AST(bool exp, str msg) {if(!exp){EPR(msg);} assert(exp);}
static inline void TAST(bool exp, str msg) {if(!exp){EPR(msg);} while(!exp){}}

bool tp_first_greater(const tiii& left, const tiii& right) {
    return tv(left, 0) > tv(right, 0);
}

int greedy_bit_fs(vector<tiii>& item, int LowLimit) {
    sort(all(item), tp_first_greater);
    int N = item.size();
    int res = INF;
    REP(p, 1<<N) {
        int ptn = p;
        int scr = 0;
        int cnt = 0;
        int lv = -1;
        REP(i,N) {
            int vi = tv(item[i], 0);
            int ci = tv(item[i], 1);
            if (ptn & 0b01) {
                scr += vi * ci + tv(item[i], 2);
                cnt += ci;
                if (scr >= LowLimit)
                    res = min(res, cnt);
            } else {
                if (lv < 0)
                    lv = i;
            }
            ptn >>= 1;
        }
        if (scr < LowLimit) {
            if (lv >= 0){
                int v = tv(item[lv], 0);
                int c = tv(item[lv], 1);
                for(int j = c; j > 0; j--) {
                    if (scr + v * j >= LowLimit) {
                        res = min(res, cnt + j);
                    }
                }
            }
        }
    }
    return res;
}


int32 main(int32 argc, char* argv[]) {
    FASTCIN();
    DEBUG_IMPORT("sample-1");


    int D, G; cin>>D>>G;
    vi P(D), C(D); REP(i,D) cin>>P[i]>>C[i];

    vector<tiii> item(D);
    REP(i,D)
        item[i] = mktp((i+1)*100, P[i], C[i]);

    int ans = greedy_bit_fs(item, G);

    cout << ans << endl;


    return 0;
}


Measured memory_bytes: 256