Problem:
Score : 200 points

Problem Statement

There is a kangaroo at coordinate 0 on an infinite number line that runs from left to right, at time 0.
During the period between time i-1 and time i, the kangaroo can either stay at his position, or perform a jump of length exactly i to the left or to the right.
That is, if his coordinate at time i-1 is x, he can be at coordinate x-i, x or x+i at time i.
The kangaroo's nest is at coordinate X, and he wants to travel to coordinate X as fast as possible.
Find the earliest possible time to reach coordinate X.

Constraints

X is an integer.

1≤X≤10^9

Input

The input is given from Standard Input in the following format:

X

Output

Print the earliest possible time for the kangaroo to reach coordinate X.

Sample Input 1

6

Sample Output 1

3

The kangaroo can reach his nest at time 3 by jumping to the right three times, which is the earliest possible time.

Sample Input 2

2

Sample Output 2

2

He can reach his nest at time 2 by staying at his position during the first second, and jumping to the right at the next second.

Sample Input 3

11

Sample Output 3

5

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>

int main(){

    int i,j,x,count,sum,temp = 0;
    int k = 0,space,min = 9999;
    scanf("%d",&x);
    for(i = 1;i < x;i++){
        temp = i;
        while(temp <= x){
            sum = temp;
            count = temp;
            //printf("temp = %d ",temp);
            space = 0;
            for(j = temp+1;space < 2;j++){
                for(k = j + space;sum < x;k++){
                    sum += k;
                    count++;
                    //printf("i = %d, sum = %d, count = %d\n",i,sum,count);
                }
                space++;
                if(min > count)
                    min = count;
            }
            temp++;
        }
    }
    //printf("%d\n",sum);
    printf("%d",min);
    return 0;
}