//Program that checks if the entered number is a fibonacci
#include<iostream.h>
bool isfibo(int);
int main()
{
int a;

char ch='y';
while(ch=='y')
{
cout<<"Enter a number :";cin>>a;
if (isfibo(a)) cout<<"The number is a part of fibonacci series";
else cout<<"The number is not a part of fibonacci series";
cout<<endl<<"Do you want to continue (y/n) :";cin>>ch;
}
return 0;
}

bool isfibo(int a)
{
if(a<0) return false;
int f1=-1;
int f2=1;
int f3;
do
{
f3=f1+f2;
f1=f2;
f2=f3;
}while(f3<a);
if(f3==a) return true;
else return false;
}