View Compilation Error

0_0_22566574_10128.cpp: In function 'int main()':
0_0_22566574_10128.cpp:131:79: error: 's' was not declared in this scope
         for(int i = 1;i <= 6;i ++) for(int j = 1;j <= 4;j ++) cin >> a[i][j], s.insert(a[i][j]);
                                                                               ^
0_0_22566574_10128.cpp:132:17: error: 's' was not declared in this scope
         if((int)s.size() != 6) {
                 ^