Calculate the N-th term  UN of the FIBONACCI sequence that is given by the recurrence relation:
\(U_1=1 \ \ \  U_2=1 \ \ \  U_N=U_{N-1}+ U_{N-2}\) (for N>2)

#include <stdio.h>

int main()
{
	int U1, U2, UN;  
 	int N; 
 	int I;  

 	do{
     		printf("Enter N : ");
    		scanf("%d", &N);
   	}while(N<1);
 
 	U1=U2=1;  
 	if (N==1)
      		UN=U1;
 	else 
		if (N==2)
      			UN=U2;
 		else
       			for (I=3 ; I<=N ; I++)
           		{
          			UN = U1+U2;
            			U1 = U2;
            			U2 = UN;
           		}
 
  	printf("Fibonacci sequence at term %d : %d\n", N, UN);

	return 0;
}

****************************************************
****************************************************

		FIBONACCI - INT / LONG

****************************************************
****************************************************

#include <stdio.h>
#include <limits.h>

int main()
{
	int U1, U2, UN;  
 	int I;  
 	UN=U1=U2=1;  
 	I=3;
 	while(1)
    	{
        	UN = U1+U2;
        	if(UN<0) break;
        	U1 = U2;
        	U2 = UN;
       		I++;
    	}
 		
  	printf("Fibonacci sequence at term %d : %d\n", --I, U2);
	return 0;
}

// Fibonacci sequence at term 46 : 1836311903




****************************************************
****************************************************

		FIBONACCI - LONG LONG

****************************************************
****************************************************

#include <stdio.h>
#include <limits.h>

int main()
{
	long long  U1, U2, UN;  
 	int I;  
 	UN=U1=U2=1;  
 	I=3;
 	while(1)
    	{
        	UN = U1+U2;
        	if(UN<0) break;
        	U1 = U2;
        	U2 = UN;
        	I++;
    	}
 		
  	printf("Fibonacci sequence at term %d : %lld\n", --I, U2);
	return 0;
}

// Fibonacci sequence at term 92 : 7540113804746346429




****************************************************
****************************************************

		FIBONACCI - DOUBLE

****************************************************
****************************************************
 
#include <stdio.h>
#include <limits.h>
#include <math.h>
int main()
{
	double  U1, U2, UN;  
 	int I;  
 	UN=U1=U2=1;  
 	I=3;
 	while(1)
    	{
        	UN = U1+U2;
        	if(isinf(UN)) break;
        	U1 = U2;
        	U2 = UN;
        	I++;
    	}
 		
  	printf("Fibonacci sequence at term %d : %e\n", --I, U2);
	return 0;
}
//Fibonacci sequence at term 1476 : 1.306989e+308





****************************************************
****************************************************

		FIBONACCI - LONG DOUBLE

****************************************************
****************************************************
 
#include <stdio.h>
#include <limits.h>
#include <math.h>
int main()
{
	long double  U1, U2, UN;  
 	int I;  
 	UN=U1=U2=1;  
 	I=3;
 	while(1)
    	{
        	UN = U1+U2;
        	if(isinf(UN)) break;
        	U1 = U2;
        	U2 = UN;
        	I++;
    	}
 		
  	printf("Fibonacci sequence at term %d : %Le\n", --I, U2);
	return 0;
}
//Fibonacci sequence at term 23601 : 9.285655e+4931