#include <stdio.h>
#define MEMO 92
 
long long unsigned int memoize[MEMO];
 
void memoInit(){
     int i;
     for(i=0;i<MEMO;i++)
          memoize[i]=-1;
     memoize[0]=1;
     memoize[1]=1;
}
 
long long unsigned int fib(int x){
     long long unsigned int ans;
     if(memoize[x]==-1){
          ans = fib(x-1) + fib(x-2);
          memoize[x] = ans;
     }
     return memoize[x];
}
 
void main(){
     int x;
     memoInit();
     printf("Calculates Fib[x].\n");
     printf("Choose x < 0 to quit.\n\n");
     printf("x: ");
     scanf("%d", &x);
 
     while(x>=0){
          if(x>(MEMO-1))
               printf("x must be less than %d\n", MEMO);
          else
               printf("Fib[%d]=%lld\n",x, fib(x));
          printf("x: ");
          scanf("%d", &x);
     }
}