text: module.exports = (input) => {
      const [width, height] = input.split(',').map(Number);
      if (width < 1 || height < 1) {
          return undefined;
      }
  
      let routeCounts = Array.from(Array(width + 1)).map((_, i) => i + 1);
      for (let y = 2; y <= height; y += 1) {
          const newRouteCounts = [1];
  
          for (let x = 1; x <= width; x += 1) {
              const routes = newRouteCounts[newRouteCounts.length - 1] + routeCounts[x];
              newRouteCounts.push(routes);
          }
  
          routeCounts = newRouteCounts;
      }
  
      return routeCounts[width];
  };
  