#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>

using namespace std;

int D, G;
int f[20][1010];

int p[20], c[20];

int main(){
	cin >> D >> G;
	
	for(register int i=1; i<=D; i++){
		cin>>p[i]>>c[i];
	}
	
	for(register int i=1; i<=D; i++){
		for(register int j=0; j<p[i]; j++){
			for(register int k=j; k<=1000; k++)
				f[i][k] = max(f[i][k], f[i-1][k-j] + j *(100 * i));
		}
		
		for(register int k=p[i]; k<=1000; k++)
			f[i][k] = max(f[i][k], f[i-1][k-p[i]] + p[i] * (100 * i) + c[i]);
	}
	
	int ans = 1000;
	for(register int i=1000; i>=0; i--)
		if(f[D][i] >= G)
			ans = i;
	
	printf("%d", ans);
}