void abort() { };
                                                                                                                                                          
                                                                             

/*
 * Recursive computation of fibonacci numbers.
 * 
 * Author: Matthias Heizmann
 * Date: 2013-07-13
 * 
 */

extern int __VERIFIER_nondet_int();


/*@ 
    requires (1);
    ensures (((((((((((((8 <= \result) && (6 == n)) || (n < 1)) || ((2 == n) && (1 <= \result))) || ((4 == n) && (3 <= \result))) || ((3 == n) && (2 <= \result))) || ((5 == n) && (5 <= \result))) || ((7 == n) && (13 <= \result))) || ((1 <= \result) && (1 == n))) || (33 < \result)) || ((21 <= \result) && (8 == n))) && (0 <= \result)));
@*/
int fibonacci(int n) {
    if (n < 1) {
        return 0;
    } else if (n == 1) {
        return 1;
    } else {
        return fibonacci(n-1) + fibonacci(n-2);
    }
}


int main() {
    int x = __VERIFIER_nondet_int();
    if (x > 46) {
        return 0;
    }
    int result = fibonacci(x);
    if (x < 9 || result >= 34) {
        return 0;
    } else {
        ERROR: {/*@ assert(0); */;abort();}
    }
}