console.log(function(args){
  let N = BigInt(args.trim());
  let name = [];
  while( N > 26n ) {
    name.unshift( Number(N % 26n) );
    N /= 26n;
  }
  name.unshift( Number(N) );
  return name.map(v=>String.fromCharCode(v+96)).join('');
}(require('fs').readFileSync('/dev/stdin', 'utf8')));
