/* program fibonacci
 the program generate fibonacci numbers
 and check for prime numbers
 Algorithm - very straightforward
 f(0) = 0
 f(1) = 1
 f(n) = f(n-1) + f(n-2) for n>1
 January 2022 (AG) */

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
{
 long long int f[100];      //using lon long int = int64
 int i, j, key, N;

// current time in seconds (begin calculations)
time_t seconds_i;
seconds_i = time (NULL);
 
N = 100;
 f[1] = 0;
 f[2] = 1;

 for (i=3; i<=N; i=i+1)
   { f[i] = f[i-1] + f[i-2];
// break if the number exceeds 2^63, i.e. long long double
   {if (f[i] > pow(2,62))
          {break;}
       };
/*   check for prime numbers */
     key =0;
     for (j=2; j< f[i-1]; j=j+1)
       {if (f[i] == (f[i]/j)*j)
          {key=1; break;}
       };
     cout << setw(3) << i << setw(20)<< f[i];
     if(key == 0)
       {cout << "  prime" << endl;}
       else {cout << endl;}
 }
// current time in seconds (end of calculations)
time_t seconds_f;
seconds_f = time (NULL);
cout << endl << "total elapsed time = "
<< seconds_f - seconds_i << " seconds" << endl << endl;
    return 0;
}