#include "bits/stdc++.h"
//#include <iostream>
//#include <vector>
//#include <string>
using namespace std;
#define setc cin.tie(0);ios::sync_with_stdio(0)
#define repi(i,a,b) for(int i=(a), i##_len=(b); i<i##_len; ++i)
#define rep(i,n) repi(i,0,n)
#define repi_(i,a,b) for(int i=(a), i##_len=(b); i<=i##_len; ++i)
#define rep_(i,n) repi_(i,0,n)
#define all(x) (x).begin(),(x).end()
#define vsort(v) sort((v).begin(), (v).end())
#define gsort(v) tsort(v); reverse((v).begin(), (v).end())
#define vrev(v) reverse((v).begin(), (v).end())
#define siz(v) ((int)(v).size())
#define ers(v, n) (v).erase((v).begin() + n)
#define cnt(v, n) count(all(v), n)
#define vmin(v) *min_element(v.begin(), v.end())
#define vmax(v) *max_element(v.begin(), v.end())
#define contain(q) !q.empty()
#define cont(q) !q.empty()
//#define qpop(q, a, b) a=q.back().first;b=q.back().second;q.pop()
//#define pqpop(p, a, b) a=q.top().first;b=q.top().second;q.pop()
#define el "\n"
#define sp " "
#define co(x) cout<<(x)<<el
#define coc(c, a, b) if(c)co((a));else co((b))
#define cosp(x) cout<<(x)<<' '
#define YES(c) coc(c,"YES", "NO")
#define Yes(c) coc(c,"Yes", "No")
#define yes(c) coc(c,"yes", "no")
#define POSSIBLE(c) coc(c, "POSSIBLE", "IMPOSSIBLE")
#define Possible(c) coc(c, "Possible", "Impossible")
#define possible(c) coc(c, "possible", "impossible")
#define inf INT_MAX
#define wildcard(T) numeric_limits<T>::min()

#define pb push_back
#define pq priority_queue
#define np next_permutation

#ifdef tqktmp_2
#define gc() getchar(); getchar()
#else
#define gc() 1
#endif
const unsigned int bf0 = (1 << 0);
const unsigned int bf1 = (1 << 1);
const unsigned int bf2 = (1 << 2);
const unsigned int bf3 = (1 << 3);
const unsigned int bf4 = (1 << 4);
const unsigned int bf5 = (1 << 5);
const unsigned int bf6 = (1 << 6);
const unsigned int bf7 = (1 << 7);

typedef long long lint;
typedef vector<int> ivec; typedef vector<string> svec;
typedef vector<vector<int>> ivvec;
typedef pair<int, int> P;

const int
	dx8[8] = { 0,1,1,1,0,-1,-1,-1 },
	dy8[8] = { 1,1,0,-1,-1,-1,0,1 },
	dx4[4] = { 0,1,0,-1 },
	dy4[4] = { 1,0,-1,0 };

template<class T>inline bool maxi(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>inline bool mini(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }

struct t {
	int s, p, c, u;
};
bool cmp(t a, t b) {//secondの値が大きい順にソートする場合
	return a.s < b.s;
}

int main() {
	setc;

	
	int d, g; cin >> d >> g;
	int inp, inc;
	vector<t> b;//s, p, c
	bool solved[10] = {};

	rep(i, d) {
		cin >> inp >> inc;
		//p.pb(inp); c.pb(inc); s.pb(100 * i * inp + inc);
		b.pb({ 100 * (i+1) * inp + inc, inp,inc, i });
	}
	vector<t> cp = b;
	sort(all(cp), cmp);
	int ans = inf, atmp = 0;
	int tmp = 0;

	for (int bit = 0; bit < (1 << d); ++bit) {
		rep(i, 10)solved[i] = 0;
		atmp = 0;
		tmp = 0;
		for (int j = 0; j < d; ++j) {
			if (bit & (1 << j)) {
				tmp += cp[j].s;
				atmp += cp[j].p;
				solved[cp[j].u] = 1;
			}
		}
		for (int j = d - 1; j >= 0; --j) {
			if (solved[j])continue;
			(b[j].u + 1) * 100;
			if (g - tmp <= 0)break;
			if (b[j].s - b[j].c >= g - tmp) {
				atmp += ceil((double)(g - tmp) / ((b[j].u + 1) * 100));
			}
			else atmp = inf;
			break;
		}
		mini(ans, atmp);

	}

	co(ans);
	gc();
}

Measured memory_bytes: 256