// verifast_options{disable_overflow_check target:ILP32}
extern void abort(void);
//@ requires true;
//@ ensures true;
void reach_error()
//@ requires false;
//@ ensures true;
{}
/*
 * Recursive computation of fibonacci numbers.
 * 
 * Author: Matthias Heizmann
 * Date: 2013-07-13
 * 
 */

extern int __VERIFIER_nondet_int(void);
//@ requires true;
//@ ensures true;


int fibonacci(int n) 
//@ requires true;
//@ ensures ((result == 0) || (0 < n));
{    if (n < 1) {
        return 0;
    } else if (n == 1) {
        return 1;
    } else {
        return fibonacci(n-1) + fibonacci(n-2);
    }
}


int main() 
//@ requires module(Fibonacci02__verifast_instrumented, true);
//@ ensures junk();
{
    //@ open_module(); 
    int x = 9;
    int result = fibonacci(x);
    if (result == 34) {
        return 0;
    } else {
        ERROR: {reach_error();abort();}
    }
 return 0; }