// verifast_options{disable_overflow_check target:ILP32}
/* extended Euclid's algorithm */
extern void abort(void);
//@ requires true;
//@ ensures true;
void reach_error()
//@ requires false;
//@ ensures true;
{}extern int __VERIFIER_nondet_int(void);
//@ requires true;
//@ ensures true;
void assume_abort_if_not(int cond) 
//@ requires true;
//@ ensures (cond != 0);
{  if(!cond) {abort();}
}
void __VERIFIER_assert(int cond) 
//@ requires (1 <= cond);
//@ ensures (1 <= cond);
{    if (!(cond)) {
    ERROR:
        {reach_error();}
    }
    return;
}

int main() 
//@ requires module(egcd_ll_valuebound50__verifast_instrumented, true);
//@ ensures junk();
{
    //@ open_module(); 
    long long a, b, p, q, r, s;
    int x, y;
    x = __VERIFIER_nondet_int();
    assume_abort_if_not(x>=0 && x<=50);
    y = __VERIFIER_nondet_int();
    assume_abort_if_not(y>=0 && y<=50);
    assume_abort_if_not(x >= 1);
    assume_abort_if_not(y >= 1);

    a = x;
    b = y;
    p = 1;
    q = 0;
    r = 0;
    s = 1;

while (1)
//@ invariant (((((b == ((q * x) + (y * s))) && (1 <= x)) && (a == ((y * r) + (p * x)))) && (1 <= y)) && ((p * s) == ((q * r) + 1)));
    {
        __VERIFIER_assert(1 == p * s - r * q);
        __VERIFIER_assert(a == y * r + x * p);
        __VERIFIER_assert(b == x * q + y * s);

        if (!(a != b))
            break;

        if (a > b) {
            a = a - b;
            p = p - q;
            r = r - s;
        } else {
            b = b - a;
            q = q - p;
            s = s - r;
        }
    }
    
    __VERIFIER_assert(a - b == 0);    
    __VERIFIER_assert(p*x + r*y - b == 0);
    __VERIFIER_assert(q*r - p*s + 1 == 0);
    __VERIFIER_assert(q*x + s*y - b == 0);
    return 0;
}