#include <iostream>
using namespace std;
int p[15], c[15], s[15];
int solve(int point, int d){
    int ans=10000, now;
    for(int i=1; i<=d; ++i){
        if(s[i]){
            --s[i];
            if(i*100*(p[i]-1)>=point) now=(point+i*100-1)/(i*100);
            else if(i*100*p[i]+c[i]>=point) now=p[i];
            else now=p[i]+solve(point-(i*100*p[i]+c[i]), d);
            ans=min(ans, now);
            ++s[i];
        }
    }
    return ans;
}
int main() {
	int D, G; cin >> D >> G;
	for(int i=1; i<=D; ++i){
	    cin >> p[i] >> c[i];
	    s[i]=1;
	}
	cout << solve(G, D) << endl;
	return 0;
}
