//C program to find sum of
//even-indices of fibonacci numbers
#include <stdio.h>

//Computes value of the first
//fibonacci numbers and stores
//the even-indices sum
int calculateEvenSum(int n)
{
    //return 0 if n is equals or less than 0
    if(n<=0)
        return 0;

    int fibo[2*n+1];
    fibo[0]=0,fibo[1]=1;

    //Initialize the result
    int sum=0;

    //Adding the remaining terms
    for(int i=2;i<=2*n;i++){
        fibo[i]=fibo[i-1]+fibo[i-2];

        //for even indices
        if(i%2==0)
            sum+=fibo[i];
    }

    //Return alternating sum
    return sum;
}

//Driver code
int main() 
{
    
    //Get n
    int n=5;

    //calculateEvenSum(n) function is computed and return
    //the sum of even - indices Fibonacci numbers.
    int sum=calculateEvenSum(n);

    //display result
    printf("Even indexed Fibonacci Sum upto %d terms =%d",n,sum);
    return 0;
}