process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////


function add(a, b) {
    return a + b;
}

function sumOfgroup(k) {
    // Return the sum of the elements of the k'th group.
   var i = 0;
   var count = 0; 
   var sum = [];
   var elementCount = 0; 
   for(var i=0; ; i++) {
       if(i%2 !== 0) {
           count++;
           if(count>k) {
              if(elementCount>=k) {
                var result = sum.reduce(add, 0);
                return result;
              } else {
                sum.push(i); 
                elementCount++;  
              }
           }
       } else {
           continue;
       }
     
   }
  
}

function main() {
    var k = parseInt(readLine());
    var answer = sumOfgroup(k);
    process.stdout.write("" + answer + "\n");

}