#include<stdio.h>
int main()
{
    int n;
    int fibo = 0;
    int sum =0;
    scanf("%d",&n);
    if(n<0)
    {
        printf("Invalid input");
        return 0;
    }
    else
    {
        while(fibo <n)
        {
            sum += fibo;
            printf("%d",sum);
        }
    }
    return 0;
}