"use strict";

function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }

function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }

function _iterableToArrayLimit(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }

function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }

function main(input) {
  var lines = input.split('\n');

  var _splitNum = splitNum(lines.shift()),
      _splitNum2 = _slicedToArray(_splitNum, 2),
      D = _splitNum2[0],
      G = _splitNum2[1];

  var data = lines.slice(0, D).map(function (line) {
    var _splitNum3 = splitNum(line),
        _splitNum4 = _slicedToArray(_splitNum3, 2),
        p = _splitNum4[0],
        c = _splitNum4[1];

    return {
      p,
      c
    };
  });
  var min = Infinity; // check for all completion.

  for (var i = 0; i < Math.pow(2, D); i++) {
    var sum = 0;
    var score = 0;
    var maxnd = -1;

    for (var d = 0; d < D; d++) {
      var used = !!(i & 1 << d);

      if (used) {
        // take all points.
        score += data[d].p * 100 * (d + 1) + data[d].c;
        sum += data[d].p;
      } else {
        maxnd = d;
      }
    }

    if (maxnd >= 0) {
      var dp = data[maxnd].p;
      var taken = Math.ceil(Math.max(0, (G - score) / (100 * (maxnd + 1))));

      if (taken >= dp) {
        // constraint is not satisfied.
        continue;
      }

      sum += taken;
    }

    if (min > sum) {
      min = sum;
    }
  }

  console.log(min);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));

function splitNum(line) {
  return line.split(/\s+/).map(function (n) {
    return parseInt(n);
  });
}
