Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

var (
	sc = bufio.NewScanner(os.Stdin)
)

func main() {
	for sc.Scan() {
		if sc.Text() == "0 0" {
			break
		}
		chunks := strings.Split(sc.Text(), " ")
		n, _ := strconv.Atoi(chunks[0])
		p, _ := strconv.Atoi(chunks[1])
		cnts := make([]int, n, n)
		for i := 0; true; i++ {
			j := i % n
			if p == 0 {
				p, cnts[j] = cnts[j], 0
			} else {
				cnts[j]++
				p--
			}

			if p == 0 {
				noneCnt := 0
				winner := 0
				for j, c := range cnts {
					if c == 0 {
						noneCnt++
					} else {
						winner = j
					}
				}
				if noneCnt == n-1 {
					fmt.Println(winner)
					break
				}
			}
		}
	}
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> P;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
// #define int long long
#define pb push_back
#define mp make_pair
#define eps 1e-9
#define INF 2000000000
#define LLINF 1000000000000000ll
#define sz(x) ((int)(x).size())
#define fi first
#define sec second
#define all(x) (x).begin(),(x).end()
#define sq(x) ((x)*(x))
#define rep(i,n) for(int (i)=0;(i)<(int)(n);(i)++)
#define repn(i,a,n) for(int (i)=(a);(i)<(int)(n);(i)++)
#define EQ(a,b) (abs((a)-(b))<eps)
#define dmp(x) cerr << __LINE__ << " " << #x << " " << x << endl;
template<class T> void chmin(T& a,const T& b){if(a>b)a=b;}
template<class T> void chmax(T& a,const T& b){if(a<b)a=b;}
template<class T>
using MaxHeap = priority_queue<T>;
template<class T>
using MinHeap = priority_queue<T,vector<T>,greater<T> >;
template<class T,class U>
ostream& operator << (ostream& os,const pair<T,U>& p){
  os << p.fi << ',' << p.sec; return os;
}
template<class T,class U>
istream& operator >> (istream& is,pair<T,U>& p){
  is >> p.fi >> p.sec; return is;
}
template<class T>
ostream& operator << (ostream &os,const vector<T> &vec){
  for(int i=0;i<vec.size();i++){
    os << vec[i];
    if(i+1<vec.size())os << ' ';
  }
  return os;
}
template<class T>
istream& operator >> (istream &is,vector<T>& vec){
  for(int i=0;i<vec.size();i++)is >> vec[i];
  return is;
}
void fastio(){
  cin.tie(0);
  ios::sync_with_stdio(0);
  cout<<fixed<<setprecision(20);
}
const ll MOD = 1000000007ll; // if inv is needed, this shold be prime.
struct ModInt{
	ll val;
	ModInt():val(0ll){}
	ModInt(const ll& v):val(((v%MOD)+MOD)%MOD){}
	ModInt exp(ll y)const{
		if(!y)return ModInt(1ll);
		ModInt a = exp(y/2ll);
		a *= a;
		if(y&1)a*=(*this);
		return a;
	}
	bool operator==(const ModInt& x)const{return val==x.val;}
	inline bool operator!=(const ModInt& x)const{return !(*this==x);}
	bool operator<(const ModInt& x)const{return val<x.val;}
	bool operator>(const ModInt& x)const{return val>x.val;}
	inline bool operator>=(const ModInt& x)const{return !(*this<x);}
	inline bool operator<=(const ModInt& x)const{return !(*this>x);}
	ModInt& operator+=(const ModInt& x){if((val+=x.val)>=MOD)val-=MOD;return *this;}
	ModInt& operator-=(const ModInt& x){if((val+=MOD-x.val)>=MOD)val-=MOD;return *this;}
	ModInt& operator*=(const ModInt& x){(val*=x.val)%=MOD;return *this;}
	ModInt operator+(const ModInt& x)const{return ModInt(*this)+=x;}
	ModInt operator-(const ModInt& x)const{return ModInt(*this)-=x;}
	ModInt operator*(const ModInt& x)const{return ModInt(*this)*=x;}
  friend istream& operator>>(istream&i,ModInt& x){ll v;i>>v;x=v;return i;}
  friend ostream& operator<<(ostream&o,const ModInt& x){o<<x.val;return o;}
};
ModInt pow(ModInt a,ll x){
  ModInt res = ModInt(1ll);
  while(x){
    if(x&1)res *= a;
    x >>= 1;
    a = a*a;
  }
  return res;
}
vector<ModInt> inv,fac,facinv;
// notice: 0C0 = 1 
ModInt nCr(int n,int r){
	assert(!(n<r));
	assert(!(n<0||r<0));
	return fac[n]*facinv[r]*facinv[n-r];
}
void init(int SIZE){
  fac.resize(SIZE+10);
  inv.resize(SIZE+10);
  facinv.resize(SIZE+10);
	fac[0]=ModInt(1ll);
	for(int i=1;i<=SIZE;i++)fac[i]=fac[i-1]*ModInt(i);
	inv[1]=ModInt(1ll);
	for(int i=2;i<=SIZE;i++)inv[i]=ModInt(0ll)-ModInt(MOD/i)*inv[MOD%i];
	facinv[0]=ModInt(1ll);
	for(int i=1;i<=SIZE;i++)facinv[i]=facinv[i-1]*inv[i];
	return;
}
bool solve(){
  int n,p;
  cin >> n >> p;
  if(n+p==0)return false;
  int C = p;
  vector<int> a(n,0);
  int cnt = 0;
  while(1){
    int id = cnt % n;
    if(C>0){
      a[id]++;
      C--;
      if(a[id]==p){
        break;
      }
    }else{
      C += a[id];
      a[id] = 0;
    }
    cnt++;
  }
  cout << cnt%n << endl;
  return true;
}
signed main(){
  fastio();
  while(solve()){}
  return 0;
}

C++: #include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
#include <climits>
#include <fstream>
#include <random>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define revrep(i, n) for(int i = (n)-1; i >= 0; i--)
#define pb push_back
#define f first
#define s second
#define chmin(x, y) x = min(x, y);
#define chmax(x, y) x = max(x, y);
#define sz(x) ((int)(x).size())

//const ll INFL = LLONG_MAX;//10^18 = 2^60
const ll INFL = 1LL<<60;
//const int INF = INT_MAX;
const int INF = 1 << 30;//10^9
const ll MOD = 1000000007;
//const ll MOD = 998244353;
double EPS = 1e-10;

vector<ll> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};

void pres(double A){printf("%.12lf\n", A);}
void BinarySay(ll x, ll y = 60){rep(i, y) cout << (x>>(y-1-i) & 1); cout << endl;}
ll cnt_bit(ll x){return __builtin_popcountll(x);}

ll pow_long(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2) res *= x;
    x *= x; k /= 2;
  }
  return res;
}

ll pow_mod(ll x, ll k){
  x %= MOD;
  ll res = 1;
  while(k > 0){
    if(k % 2){
      res *= x; res %= MOD;
    }
    x *= x; x %= MOD;
    k /= 2;
  }
  return res;
}

void solve(){
  while(true){
    int n, p;
    cin >> n >> p;
    int all = p;
    if(n == 0 && p == 0) return;
    vector<int> cnt(n, 0);
    rep(i, 1000000){
      int t = i % n;
      if(p){
        p--;
        cnt[t]++;
        if(p == 0 && cnt[t] == all){
          cout << t << endl;
          break;
        }
      }else{
        p += cnt[t];
        cnt[t] = 0;
      }
    }
  }
}

int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  solve();
}

C++: #include <iostream>
using namespace std;
int main(){
  int n,p,i,stc;
  int hstc[50];

  while(1){
    cin >> n >> p;
    if (n==0&&p==0) break;

    stc = p;
    for (i=0;i<n;i++) hstc[i]=0;
    i=0;
    while(1){
      if (stc >0){
	stc--;
	hstc[i]++;
	if (hstc[i]==p) break;
      }else{
	stc=hstc[i];
	hstc[i]=0;
      }
      i++;
      if (i==n) i=0;
    }
    cout << i << endl;
  }
  return 0;
}

C++: #include <stdio.h>
int main(){
  
  int player[51];
  int n,p,pool=0,i;
  for(;;){
  scanf("%d %d",&n,&p);

  if(n==0&&p==0){
    break;
  }
  pool=p;
 
  for(;;){

    for(i=0;i<=n-1;i++){
      if(pool==0){
	pool=player[i];
	player[i]=0;
	continue;
      }
      if(pool==1&&player[i]==p-1){
	break;
      }

      if (pool!=0){
	pool=pool-1;
	player[i]+=1;
      }
    }
    if(pool==1&&player[i]==p-1){
      break;
    }

  }
  printf("%d\n",i);
  pool=0;
  player[i]=0;
  }
  return 0;
}

C++: #include<iostream>
using namespace std;
int n,p;
int solve(){
  int cnt=0;
  int t[50]={};
  for(int i=0;;i=(i+1)%n){
    if(p==0){
      if(t[i]>0)cnt--;
      p=t[i];
      t[i]=0;
    }else{
      if(t[i]==0)cnt++;
      t[i]++;
      p--;
      if(p==0&&cnt==1)return i;
    }
  }
}
int main(){
  while(1){
    cin>>n>>p;
    if(n==0&&p==0)break;
    cout<<solve()<<endl;
  }
  return 0;
}