// verifast_options{disable_overflow_check target:ILP32}

extern void abort(void);//@ requires true; 
//@ ensures true;


extern void __assert_fail (const char *__assertion, const char *__file,
      unsigned int __line, const char *__function)
     __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__noreturn__));
extern void __assert_perror_fail (int __errnum, const char *__file,
      unsigned int __line, const char *__function)
     __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__noreturn__));
extern void __assert (const char *__assertion, const char *__file, int __line)
     __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__noreturn__));

void reach_error() //@ requires false; 
//@ ensures true;
{ ((void) sizeof ((0) ? 1 : 0), __extension__ ({ if (0) ; else __assert_fail ("0", "assert.h", 3, __extension__ __PRETTY_FUNCTION__); })); }
extern void abort(void);
void assume_abort_if_not(int cond) //@ requires true; 
//@ ensures true;
{
  if(!cond) {abort();}
}
void __VERIFIER_assert(int cond) //@ requires (cond != 0); 
//@ ensures (cond != 0);
{
  if (!(cond)) {
      ERROR: {reach_error();abort();}
  }
  return;
}
int __VERIFIER_nondet_int();//@ requires true; 
//@ ensures true;

int main() //@ requires module(bhmr2007__verifast_instrumented_modified, true); 
//@ ensures junk();
{
    int i, n, a, b;
    i = 0; a = 0; b = 0; n = __VERIFIER_nondet_int();
    if(!(n >= 0 && n <= 1000000)) return 0;
    while (i < n)//@ invariant (((b + a) <= (n * 3)) && ((b + a) == (i * 3)));
 {
        if (__VERIFIER_nondet_int()) {
            a = a + 1;
            b = b + 2;
        } else {
            a = a + 2;
            b = b + 1;
        }
        i = i + 1;
    }
    __VERIFIER_assert(a + b == 3*n);
    return 0;
}