// verifast_options{disable_overflow_check target:ILP32}
extern void abort(void);
//@ requires true;
//@ ensures true;
void reach_error()
//@ requires false;
//@ ensures true;
{}
/*
 * Implementation the McCarthy 91 function.
 * http://en.wikipedia.org/wiki/McCarthy_91_function
 * 
 * Author: Matthias Heizmann
 * Date: 2013-07-13
 * 
 */

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


int f91(int x) 
//@ requires true;
//@ ensures (((result == 91) && (x <= 100)) || ((91 <= result) && (x == (result + 10))));
{    if (x > 100)
        return x -10;
    else {
        return f91(f91(x+11));
    }
}


int main() 
//@ requires module(McCarthy91_2__verifast_instrumented, true);
//@ ensures junk();
{
    //@ open_module(); 
    int x = __VERIFIER_nondet_int();
    int result = f91(x);
    if (result == 91 || x > 101 && result == x - 10) {
        return 0;
    } else {
        ERROR: {reach_error();abort();}
    }
 return 0; }