#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

typedef long long ll;
typedef pair<int,int> ii;
typedef tree<ii,null_type,less<ii>,rb_tree_tag,tree_order_statistics_node_update> indexed_set;

int main() {
	cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
	int D,G; cin>>D>>G;
	vector<int> p(D), c(D);
	for (int i=0; i<D; i++)
		cin>>p[i]>>c[i];
	int ret=INT_MAX;
	for (int bt=0; bt<(1<<D); bt++) {
		int cur=0, val=0;
		for (int i=0; i<D; i++)
			if(bt&(1<<i))
				cur+=p[i], val+=p[i]*(i+1)*100+c[i];
		int diff=max(0,G-val);
		for (int i=D-1; i>=0; i--) {
			if(bt&(1<<i))
				continue;
			int pt=(i+1)*100;
			int tmp=min((diff+pt-1)/pt,p[i]-1);
			cur+=tmp; diff=max(0,diff-pt*tmp);
		}
		if(diff>0)
			continue;
		ret=min(ret,cur);
	}
	cout<<ret<<"\n";
	return 0;
}