const fs = require('fs');
fs.readFile('input', (err, data) => {
  if (err) throw err;
  let groups = data.toString().split("\n\n").map( (group) => new Set( group.replace(/\r?\n|\r/g, "").split('') ) );
  console.log(groups.reduce((sum, group) => sum + group.size, 0));
});