/* Geometric Series computes x = sum(z^k)[k=0..k-1], y = z^(k-1) */ void abort() { }; extern 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 z, k; unsigned long long x, y, c; z = __VERIFIER_nondet_int(); assume_abort_if_not(z>=0 && z<=2); k = __VERIFIER_nondet_int(); assume_abort_if_not(k>=0 && k<=2); x = 1; y = 1; c = 1; /*@ loop invariant ((((z <= 2) && (((((((__int128) z * x) + (((__int128) 18446744073709551615U * z) * y)) + ((unsigned __int128) 18446744073709551615U * x)) + 1) % ((unsigned __int128) 1 << 64)) == 0)) && (0 <= z))); @*/ while (1) { __VERIFIER_assert(1 + x*z - x - z*y == 0); if (!(c < k)) break; c = c + 1; x = x * z + 1; y = y * z; } __VERIFIER_assert(1 + x*z - x - z*y == 0); return 0; }