double sum = 0.0; double speed = 7.0; const double low = 0.98;

if (s + x < 7.0) {
    printf("n");
    return 0;
}

sum = 7.0;
while (s - x > sum + 1e-6) {
    speed *= low;
    sum += speed;
}

double nextSpeed = speed * low;
if (nextSpeed > 2.0 * x + 1e-6) {
    printf("n");
} else {
    printf("y");
}

return 0;