mad_progression.cpp

//============================================================================
// Name        : MadProgression.cpp
// Author      : magicsih
// Version     :
// Copyright   : 
// Description : Mad Progression in C++, Ansi-style
//============================================================================
#include <iostream>
#include <fstream>

using namespace std;

int main() {

   long long position = 4;

   std::ifstream fin;
   fin.open("input.txt");
   fin >> position;
   fin.close();

   long long accumulator = 1;
   long long supplement = 1;

   while (accumulator < position) {
      accumulator += supplement;
      if (accumulator <= position) {
         supplement++;
      }
   }

   std::ofstream fout;
   fout.open("output.txt");
   fout << supplement;
   fout.close();

   return 1;
}

Algorithm : Mad Progression

Condition

1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, ...

Input

4

Output

3