#include <vector>#include <map>#include <set>#include <deque>#include <stack>#include <bitset>#include <algorithm>#include <sstream>#include <iostream>#include <cstdio>#include <queue>#include <cmath>#include <cstdlib>#include <cstring>#include <ctime>#include <string>#include <cassert>using namespace std;#define inf 2000000000#define ll __int64#define add 10009int f_min(int x,int y){return x<y?x:y;}int f_max(int x,int y){return x>y?x:y;}int f_abs(int x){if(x<0) x=-x;return x;}char s[110];void swap1(int x,int y){ char c; c=s[x]; s[x]=s[y]; s[y]=c;}void swap2(int x,int y){ char c; if(s[y]=='B') s[y]='W'; else s[y]='B'; c=s[x]; s[x]=s[y]; s[y]=c;}int len;int ans;bool cheak(){ int i; bool flag1=false; bool flag2=false; for(i=0;s[i];i++){ if(!flag1&&s[i]=='B') flag1=true; if(flag1&&(s[i]=='W')) flag2=true; if(flag2&&s[i]=='B') return false; } return true;}void f(int pre,int x,int step){ int i; int tx; if(step>=ans) return; if(pre!=1&&pre!=-1&&cheak()){ ans=step; return; } if(step>=9) return; if(pre!=1 &&x-1>=0){ swap1(x,x-1); f(-1,x-1,step+1); swap1(x,x-1); } if(pre!=-1&&x+1<len){ swap1(x,x+1); f(1,x+1,step+1); swap1(x,x+1); } if(pre!=2 &&x-2>=0){ swap2(x,x-2); f(-2,x-2,step+1); swap2(x-2,x); } if(pre!=-2&&x+2<len){ swap2(x,x+2); f(2,x+2,step+1); swap2(x+2,x); }}int main(){ int n,m,cas=0,u,v,x,y; while(~scanf("%s",s),s[0]-'-'){ len=strlen(s); for(int i=0;s[i];i++){ if(s[i]=='F') {x=i;break;} } ans=10; f(-222,x,0); if(ans==10) ans=-1; printf("%d. %dn",++cas,ans); } return 0;}
