console.log((args=>{
  const [[D,G],...tmp] = args.trim().split('\n').map( r=>r.split(' ').map(v=>v|0));
  const p = [], c = [];
  for ( let i = 0; i < D; i++ ) {
    p.push( tmp[i][0] );
    c.push( tmp[i][1] );
  }
  let min = Infinity;
  for ( let bit = 0; bit < 1<<D; bit++ ) {
    let q = 0, s = 0, x = 0;
    for ( let i = 0; i < D; i++ ) {
      if ( bit & 1<<i ) {
        q += p[i];
        s += (i+1) * 100 * p[i] + c[i];
      } else x = i;
    }
    if ( s >= G && min > q ) {
      min = q;
      continue;
    }
    for ( let i = 1; i < p[x]; i++ ) {
      if ( G <= s + i*(x+1)*100 && min > q + i ) {
        min = q + i;
        break;
      }
    }
  }
  return `${min}`;
})(require('fs').readFileSync('/dev/stdin', 'utf8')));
