void abort() { }; extern int __VERIFIER_nondet_int(); /*@ requires (1); ensures ((cond != 0)); @*/ void assume_abort_if_not(int cond) { if(!cond) {abort();} } /*@ requires ((1 <= cond)) && (cond != 0); ensures ((1 <= cond)) && (1); @*/ void __VERIFIER_assert(int cond) { if (!(cond)) { ERROR: {/*@ assert(0); */;} } return; } int main() { int x, y; long long a, b, p, q, r, s; x = __VERIFIER_nondet_int(); assume_abort_if_not(x>=0 && x<=1); y = __VERIFIER_nondet_int(); assume_abort_if_not(y>=0 && y<=1); assume_abort_if_not(x >= 1); assume_abort_if_not(y >= 1); a = x; b = y; p = 1; q = 0; r = 0; s = 1; /*@ loop invariant ((((((((((a == 1) && (b == 0)) && (p == 0)) && (y == 1)) && (r == 1)) && (x == 1)) && (q == 1)) && (((__int128) s + 1) == 0)) || ((((((((a == 1) && (r == 0)) && (b == 1)) && (y == 1)) && (s == 1)) && (x == 1)) && (q == 0)) && (p == 1)))); @*/ while (1) { if (!(b != 0)) break; long long c, k; c = a; k = 0; /*@ loop invariant ((((((((((((a == 1) && (r == 0)) && (b == 1)) && (y == 1)) && (s == 1)) && (x == 1)) && (k == 1)) && (q == 0)) && (c == 0)) && (p == 1)) || ((((((((((a == 1) && (r == 0)) && (b == 1)) && (y == 1)) && (k == 0)) && (s == 1)) && (x == 1)) && (q == 0)) && (c == 1)) && (p == 1)))); @*/ while (1) { if (!(c >= b)) break; long long d, v; d = 1; v = b; /*@ loop invariant (((((((((((((a == 1) && (r == 0)) && (y == 1)) && (k == 0)) && (s == 1)) && (v == 1)) && (b == y)) && (d == 1)) && (q == 0)) && (a == x)) && (c == x)) && (p == 1))); @*/ while (1) { __VERIFIER_assert(a == y * r + x * p); __VERIFIER_assert(b == x * q + y * s); __VERIFIER_assert(a == k * b + c); __VERIFIER_assert(v == b * d); if (!(c >= 2 * v)) break; d = 2 * d; v = 2 * v; } c = c - v; k = k + d; } a = b; b = c; long long temp; temp = p; p = q; q = temp - q * k; temp = r; r = s; s = temp - s * k; } __VERIFIER_assert(p*x - q*x + r*y - s*y == a); return 0; }