SegiTiga

/*
    Task    : Segi Tiga
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 04 January 2023 [20:46]
*/
#include<bits/stdc++.h>
using namespace std;
char a[260];
int dp[260][260][3];    //0 1 2
int res[3][3] = {2,1,0,2,1,1,1,2,1};
int recur(int i,int j,int target){
    if(i == j){
        if(a[i]-'0' == target)  return 1;
        else                    return -1;
    }
    if(dp[i][j][target] != 0)   return dp[i][j][target];
    for(int k=i;k<j;k++){
        for(int x=0;x<=2;x++){
            for(int y=0;y<=2;y++){
                // อยากให้ทางซ้ายได้ค่าเป็น x
                // อยากให้ทางขวาได้ค่าเป็น y
                if(res[x][y] != target) continue;
                if(recur(i,k,x) == 1 && recur(k+1,j,y) == 1){
                    return dp[i][j][target] = 1;
                }
            }
        }
    }
    return dp[i][j][target] = -1;
}
int main(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    int q=20;
    while(q--){
        int n;
        cin >> n >> a+1;
        memset(dp,0,sizeof dp);
        if(recur(1,n,0) == 1)   cout << "yes\n";
        else                    cout << "no\n";

    }
    return 0;
}