#include <iostream>#include <string>using namespace std;#define MAX 151int sov[MAX][MAX],rig[MAX];bool tag[MAX];bool search(int low,int up){ if(sov[low][up] != -1) return sov[low][up]==0?false:true; if(low > up)return true; if(tag[low]){ //情况1 sov[low+1][up] = search(low+1,up); if(sov[low+1][up])return true; } int i,j; i = rig[low]; while(i != -1 && i < up) //情况2 { sov[low][i] = search(low,i); sov[i+1][up] = search(i+1,up); if(sov[low][i] && sov[i+1][up])return true; i = rig[i]; } if(i == -1 || i > up)return false; if(i == up) //情况3 { sov[low+1][up-1] = search(low+1,up-1); if(sov[low+1][up-1])return true; for(j = rig[low];j < up;j = rig[j]) { sov[low+1][j-1] = search(low+1,j-1); sov[j+1][up-1] = search(j+1,up-1); if(sov[low+1][j-1] && sov[j+1][up-1])return true; } } return false;}int main(){ char s[MAX]; int i,j,n,vis[30]; while(scanf("%s",&s)!=EOF) { memset(tag,0,sizeof(tag)); j = 0; for(i = 1;i < strlen(s);i ++){ if(s[i] == s[j]) tag[j] = true; else s[++j] = s[i]; } n = j+1; memset(rig,-1,sizeof(rig)); memset(vis,-1,sizeof(vis)); for(i = 0; i < n;i ++){ if(vis[s[i]-'A'] == -1) vis[s[i]-'A'] = i; else{ rig[vis[s[i]-'A']] = i; vis[s[i]-'A'] = i; } } memset(sov,-1,sizeof(sov)); for(i = 0;i < n;i ++) sov[i][i] = tag[i]; if(search(0,n-1))printf("solvablen"); else printf("unsolvablen"); } return 0;}
