```
bool isStrobogrammatic(string num) {
for (int i = 0, j = num.size()-1; i<=j; i++, j--){
if (num[i] == num[j]){
if (num[i] != '0' && num[i] != '1' && num[i] != '8') return false;
}
else if (!((num[i] == '6' && num[j] == '9') || (num[i] =='9'&&num[j] =='6'))) return false;
}
return true;
}
```