#include using namespace std; typedef long long ll; typedef pair pii; #define pb push_back #define mp make_pair #define rep(i,n) for(int i=0;i<(n);++i) const int mod=1000000007; int main(){ cin.tie(0); ios::sync_with_stdio(false); int a,b;cin >> a >> b; cout << b%a << endl; }