#pragma GCC optimize("O3", "unroll-loops")
//#pragma GCC target("avx2")
#pragma optimize("fast-math")

#include <bits/stdc++.h>
#include <stdio.h>

using namespace std;
#define endl '\n'
#define ull unsigned long long
#define si short int
#define ll long long
#define ld long double
#define pb push_back
#define pii pair<int, int>
#define pdd pair<double, double>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define piii pair<pair<int, int>, int>
#define all(vec) (vec).begin(), (vec).end()
#define piiii pair<pair<int, int>, pair<int, int>>
#define fr(a, from, c) for(int a=(from); (a)<(c); (a)++)

/*-----------------------------------------------------SegTree---------------------------------------------*/

/*
int mxn11 = (int) (3e5 + 2);
vector<int> t(4 * mxn11 + 1, 0);
vector<int> tAdd(4 * mxn11 + 1, 0);

void build(int v, int vl, int vr) {
    if (vl == vr) {
        t[v] = vl;
    } else {
        int tmp = (vl + vr) >> 1;
        build((v << 1), vl, tmp);
        build((v << 1) + 1, tmp + 1, vr);
        t[v] = 0;
    }
}

void push(int v){
    tAdd[2*v]+=tAdd[v];
    tAdd[2*v+1]+=tAdd[v];
    t[v]+=tAdd[v];
    tAdd[v]=0;
}
int get(int v, int vl, int vr, int l, int r) {
    if (l > r) return 0;
    if (vl == l && vr == r) {
        return t[v]+tAdd[v];
    }
    int tmp = (vl + vr) >> 1;
    push(v);
    int a = get(v << 1, vl, tmp, l, mun(tmp, r));
    int b = get((v << 1) + 1, tmp + 1, vr, mux(tmp + 1, l), r);
    return a+b;
}

void update(int v, int vl, int vr, int l, int r, int x){
    if(l>r) return;
    if(vl==l && vr==r){
        tAdd[v]+=x;
        return;
    }
    int tmp=(vl+vr)/2;
    push(v);
    update(2*v, vl, tmp, l, min(r, tmp), x);
    update(2*v+1, tmp+1, vr, max(l, tmp+1), r, x);
    t[v] = t[2 * v] + tAdd[2 * v] + t[2 * v + 1] + tAdd[2 * v + 1];
}
*/


/*-----------------------------------------------------SegTree---------------------------------------------*/
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

/*-----------------------------------------------------OperatorsOverloaded---------------------------------*/
template<typename T, typename U>
ostream &operator<<(ostream &o, pair<T, U> p) {
    o << p.first << " " << p.second << endl;
    return o;
}

template<typename T>
istream &operator>>(istream &o, vector<T> &arr) {
    for (int i = 0; i < arr.size(); i++) o >> arr[i];
    return o;
}

template<typename T>
ostream &operator<<(ostream &o, vector<T> &arr) {
    for (int i = 0; i < arr.size(); i++) o << arr[i] << " ";
    o << endl;
    return o;
}
/*-----------------------------------------------------OperatorsOverloaded---------------------------------*/
/*#ifdef ALLOC_LOCAL
const int ML_ = 450;
char mem_[ML_ * 1024 * 1024];
size_t _ptr = 0, _magic = 21323400;
void * operator new(size_t cnt) { if (_ptr + cnt < sizeof mem_) { _ptr += cnt; return  mem_ + _ptr - cnt; } else { assert(false);  _ptr = cnt + _magic; return mem_ + _magic; } }
void operator delete(void *) {}
#endif //ALLOC_LOCAL*/
int mux(int a, int b) {
    if (a > b) return a;
    return b;
}

int mun(int a, int b) {
    if (a < b) return a;
    return b;
}
/*-----------------------------------------------------MATH------------------------------------------------*/
inline ll gcd(ll a, ll b) {
    while (b) {
        a %= b;
        swap(a, b);
    }
    return a;
}

inline ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }


inline ll gcdex(ll a, ll b, ll &x, ll &y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    ll xx, yy;
    ll gc = gcdex(b, a % b, yy, xx);
    x = xx;
    y = yy - (a / b) * xx;
    return gc;
}

inline ll pwm(ll xx, ll pow, ll MD) {
    if (pow < 0) { pow = pow % (MD - 1) + MD - 1; }
    ll mlt = 1;
    while (pow) {
        if (pow & 1) {
            mlt *= xx;
            mlt %= MD;
        }
        xx *= xx;
        pow >>= 1;
        xx %= MD;
    }
    return mlt;
}

inline int inv(ll r, int _mod) { return pwm(r % _mod, _mod - 2, _mod); }

inline int64_t hilbertOrder(int x, int y, int pow, int rotate) {
    if (pow == 0) {
        return 0;
    }
    int hpow = 1 << (pow - 1);
    int seg = (x < hpow) ? (
            (y < hpow) ? 0 : 3
    ) : (
                      (y < hpow) ? 1 : 2
              );
    seg = (seg + rotate) & 3;
    const int rotateDelta[4] = {3, 0, 0, 1};
    int nx = x & (x ^ hpow), ny = y & (y ^ hpow);
    int nrot = (rotate + rotateDelta[seg]) & 3;
    int64_t subSquareSize = int64_t(1) << (2 * pow - 2);
    int64_t ans = seg * subSquareSize;
    int64_t add = hilbertOrder(nx, ny, pow - 1, nrot);
    ans += (seg == 1 || seg == 2) ? add : (subSquareSize - add - 1);
    return ans;
}

/*-----------------------------------------------------MATH------------------------------------------------*/
const int mod=1e9+7;

void solve() {
    ll n,k;
    cin>>n>>k;
    ll s=n/k;
    ll ans=min(n-s*k, (s+1)*k-n);
    cout<<ans<<endl;
}

void testcases(int n) {
    n = 1 - n;
    if (!n) cin >> n;
    for (int i = 0; i < n; i++) {
        solve();
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    //freopen("C:\\Users\\Maximus\\CLionProjects\\Codeforces\\BestTeam\\output.txt", "r", stdin);
    //f=fopen("C:\\Users\\Maximus\\CLionProjects\\Codeforces\\BestTeam\\output.txt", "w");
    //freopen("C:\\Users\\Maximus\\CLionProjects\\Codeforces\\BestTeam\\output.txt", "w", stdout);

    unsigned int beg_time = clock();
    testcases(0);
    // 0 - no t, 1 - with t

    unsigned int end_time = clock();
    //cout << endl << endl << end_time - beg_time;
    return 0;
}

Measured memory_bytes: 256