#include <bits/stdc++.h>
using namespace std;

#define _ ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define itloop(it,x) for(auto it=x.begin();it!=x.end();it++)
#define reloop(i,e,b) for(auto i=e;i>=b;i--)
#define loop(i,b,e) for(auto i=b;i<=e;i++)
#define ALL(x) x.begin(),x.end()
#define SZ(x) x.size()
#define PB push_back
#define MP make_pair
#define F first
#define S second
typedef long long LL;
typedef vector<int> VI;

LL dmg(string s) {
   LL damage=1,cnt=0;
   loop(i,0,s.length()-1) {
      if(s[i] == 'S')
         cnt += damage;
      else
         damage *= 2;
   }
   return cnt;
}

string update(string s) {
   bool updated=false;
   reloop(i,s.length()-1,1) {
      if(s[i] == 'S' && s[i-1] == 'C') {
         swap(s[i],s[i-1]);
         updated = true;
         break;
      }
   }
   if(updated)
      return s;
   else
      return "0";
}

void solve(string s,LL d,int i) {
   int cnt = 0;
   if(dmg(s) <= d)
      cout << "Case #" << i << ": 0\n";
   else {
      while(s != "0" && dmg(s) > d) {
         s = update(s);
         cnt++;
      }
      if(s != "0")
         cout << "Case #" << i << ": " << cnt << "\n";
      else
         cout << "IMPOSSIBLE\n";
   }
}

LL t,d;
string s;

int main() {
   cin >> t;
   loop(i,1,t) {
      cin >> d >> s;
      solve(s,d,i);
   }
}