#include #include using namespace std; using namespace atcoder; #define ll long long #define rep(i, n) for (int i = 0; i < (n); i++) #define coutf(f) cout << fixed << setprecision(f) #define all(v) (v).begin(), (v).end() #define rall(v) (v).rbegin(), (v).rend() int main() { ll s, k; cin >> s >> k; cout << s % k << endl; return 0; }