function montRevert(x) {
  var r = new BigInteger()
  x.copyTo(r)
  this.reduce(r)
  return r
}
function montRevert(x) {
  var r = new BigInteger()
  x.copyTo(r)
  this.reduce(r)
  return r
}
function montRevert ( x ) { var r = new BigInteger ( ) x . copyTo ( r ) this . reduce ( r ) return r }
x/R mod m
x / R mod m