"use strict";
    
const div = (a, b) => Math.floor(a / b);

const main = arg => {
    arg = arg.trim().split("\n");
    const D = parseInt(arg[0].split(" ")[0]);
    const G = parseInt(arg[0].split(" ")[1]);
    
    const scores = arg.slice(1, D + 1);
    
    let p = [];
    let c = [];
    
    for(let i=0; i<D; i++) {
        let temp = scores[i].split(" ");
        p[i] = temp[0];
        c[i] = temp[1];
    }
    
    let ans = 1e9;
    
    for (let mask = 0; mask < (1 << D); ++mask) {
        let s = 0, num = 0, rest_max = -1;
        for (let i = 0; i < D; ++i) {
            if (mask >> i & 1) {
                s += 100 * (i + 1) * p[i] + c[i];
                num += p[i];
            } else rest_max = i;
        }
        if (s < G) {
            let s1 = 100 * (rest_max + 1);
            let need = div(G - s + s1 - 1, s1);
            if (need >= p[rest_max]) continue;
            num += need;
        }
        ans = Math.min(ans, num);
    }
    
    console.log(ans);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));