```
string longestPalindrome(string a){
int first = 0;
int last = 0;
int length = a.length();
int i = 0;
int j =length-1;
bool find = true;
while(i < length)
{
for(j = length-1;j > i;j--)
{
if(a[j] == a[i]){
int m = i;
int n = j;
while(m < n)
{
if(a[n] != a[m]){
find = false;
break;
}
m++;n--;
}
if(find &&((last - first) < (j - i)))
{
first = i;
last = j;
break;
}
}
}
if((last - first + 1) == (length -i))
break;
i++;
find = true;
}
string result = a.substr(first,last-first+1);
return result;
}
```