process.stdin.resume();
process.stdin.setEncoding('utf8');

var input_lines = []; 
var reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
reader.on('line', (line) => {
  input_lines.push(line);
});
reader.on('close', () => {
  var height = Number(input_lines[0].split(' ')[0]);
  var width = Number(input_lines[0].split(' ')[1]);
  var count = 0;

  if(height === 1 || width === 1){
    console.log (1);
  }else{
    var odd = Math.ceil(height / 2);
    var even = height - odd;
    var movable_even = Math.floor(width / 2);
    var movable_odd = width % 2 === 1 ? movable_even + 1 : movable_even
    
    count = (even * movable_even) + (odd * movable_odd);
    
    console.log(count);
  }
});