3281

// include file
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <ctime>

#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <bitset>

#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <list>
#include <functional>

using namespace std;

// typedef
typedef __int64 LL;

// 
#define read freopen("in.txt","r",stdin)
#define write freopen("out.txt","w",stdout)

#define Z(a,b) (a<<b)
#define Y(a,b) (a>>b)

const double eps = 1e-6;
const double INFf = 1e100;
const int INFi = 1000000000;
const LL INFll = (LL)1<<62;
const double Pi = acos(-1.0);

template<class T> inline T sqr(T a){return a*a;}
template<class T> inline T TMAX(T x,T y)
{
	if(x>y) return x;
	return y;
}
template<class T> inline T TMIN(T x,T y)
{
	if(x<y) return x;
	return y;
}
template<class T> inline T MMAX(T x,T y,T z)
{
	return TMAX(TMAX(x,y),z);
}
template<class T> inline T MMIN(T x,T y,T z)
{
	return TMIN(TMIN(x,y),z);
}
template<class T> inline void SWAP(T &x,T &y)
{
	T t = x;
	x = y;
	y = t;
}


// code begin
short DP[152][152];
char in[152];
int N;

int dfs(int l,int r)
{	
	if(l>r)
		return 2; // 行
	if(l==r)
		return 1; //不行
	if(DP[l][r])
		return DP[l][r];

	int ans = 0,ans1,ans2;
	DP[l][r] = 1;
	if(in[l]==in[r])
	{
		ans = dfs(l+1,r-1); //AxA规则
		if(ans==2)
		{
			DP[l][r] = ans;
		}
		else
		{
			for(int i=l+1;i<=r-1;i++) //AxAyA规则 
			{
				if(in[i]==in[l])
				{
					ans1 = dfs(l+1,i-1);
					if(ans1!=2) continue;
					ans2 = dfs(i+1,r-1);
					if(ans1==ans2 && ans1==2)
					{
						DP[l][r] = ans1;
						break;
					}
				}
			}
		}
	}
	else
	{
		for(int i=l+1;i<=r-2;i++) //xy规则
		{
			if(in[l]==in[i] )
			{
				ans1 = dfs(l,i);
				if(ans1!=2) continue;
				ans2 = dfs(i+1,r);
				if(ans1==ans2&&ans1==2)
				{
					DP[l][r] = 2;
					break;
				}
			}
		}
	}
	return DP[l][r];
}

int main()
{
	read;
	write;
	while(scanf("%s",in)==1)
	{
		memset(DP,0,sizeof(DP));
		N  = strlen(in);
		if( dfs(0,N-1)==2 )
		{
			printf("solvable\n");
		}
		else
		{
			printf("unsolvable\n");
		}
	}
	return 0;
}