int dyqys(int a, int n) { int k[3], r[3], q; k[1] = 0, k[2] = 1; r[1] = n, r[2] = a; while (r[2] != 1) { r[0] = r[1], r[1] = r[2]; k[0] = k[1], k[1] = k[2]; if (r[1] == 0) return -1; q = r[0] / r[1]; r[2] = r[0] % r[1]; k[2] = (k[0] - q * k[1]) % n; if (k[2] < 0) k[2] += n; } return k[2]; }