function main(input) {
  input=input.trim();
  const x = parseInt(input.split("\n")[0], 10);
  var arr=[]
  for(var i=0; i<32; i++){
    arr.push((i+1)*(i+1))
  }
  for(var i=0; i<10; i++){
    arr.push((i+1)*(i+1)*(i+1))
  }
  for(var i=0; i<5; i++){
    arr.push((i+1)*(i+1)*(i+1)*(i+1))
  }
  arr.push(32,243,64,729,128,256,512)
  arr.sort(function(a,b){
    if( a < b ) return -1;
    if( a > b ) return 1;
    return 0;
  });
  for(var i=0; i<arr.length; i++){
    if(arr[i]<=x){
      ans=arr[i]
    }else{
      break
    }
  }
  console.log(ans);

}


main(require('fs').readFileSync('/dev/stdin', 'utf8'));
