text: 'use strict'
  
  process.stdin.resume();
  process.stdin.setEncoding('utf-8');
  
  const readline = require('readline');
  
  const rl = readline.createInterface({
      input: process.stdin,
      output: console.log
  });
  
  class Polygon {
      constructor(arr) {
          this.array = arr;
      }
      perimeter() {
          return this.array.reduce((previous, current, index, array) => previous + current);
      }
  }
  
  rl.on('line', input => {
      let pol = new Polygon(input.trim().split(' ').map(s => parseInt(s)));
      console.log(pol.perimeter());
  
      rl.close();
  });
  