class Answer {
  constructor(input) {
    const data = input.trim().split(' ');
    this.X = Number(data[0]);
    this.Y = Number(data[1]);
    this.Z = Number(data[2]);
  }

  main() {
    let count = 0;
    count += this.X > this.Y ? this.Y : this.X;
    let diff = Math.abs(this.X - this.Y);
    if(this.Z >= diff) {
      count += diff;
      count += Math.floor((this.Z - diff)/2);
    }else {
      count += this.Z;
    }
    this.dest(count);
  }

  dest(ans) {
    console.log(ans);
  }
}

new Answer(require('fs').readFileSync('/dev/stdin', 'utf-8')).main();