// verifast_options{disable_overflow_check target:ILP32}

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

extern void __assert_fail(const char *, const char *, unsigned int, const char *) __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__noreturn__));
void reach_error() //@ requires false; 
//@ ensures true;
{ __assert_fail("0", "sum_2x3-2.c", 3, "reach_error"); }

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

int main(void) //@ requires module(sum_2x3_2__verifast_instrumented_modified, true); 
//@ ensures junk();
{
  int a = 2;
  int b = 3;
  int result = sum(a, b);
  if (result != a + b) {
    ERROR: {reach_error();abort();}
  }
}