"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const D = parseInt(arg[0].split(" ")[0]);
    const G = parseInt(arg[0].split(" ")[1]) / 100;
    
    const scores = arg.slice(1, D + 1);
    
    let p, c, sum;
    
    for(let i=0; i<D; i++) {
        let temp = scores[i].split(" ");
        p[i] = temp[0];
        c[i] = temp[1] / 100;
        // その点数帯を全完したときのスコア
        sum[i] = (parseInt(i) + 1) * p[i] + c[i];
    }
    
    let answer = 1e9;
    
    for(let i=0; i<(1 << D); i++) {
        let add = 0;
        let cnt = 0;
        
        for(let j=0; j<D; j++) {
            if(i & (1 << j)) {
                add += sum[j];
                cnt += p[j];
            }
        }
        
        if(add >= G) {
            answer = Math.min(answer, cnt);
            continue;
        }
        
        for(let j=D-1; j>=0; j--) {
            if(!(i & (1 << j))) {
                if(add + sum[j] - c[j] <= G) {
                    break;
                } else  {
                    cnt += (G - add + parseInt(j) + 1 -1) / (j + 1);
                    answer = Math.min(answer, cnt);
                    break;
                }
            }
        }
    }
    
    console.log(answer);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));