class Solution {
public:
    int countSubstrings(string s) {
        int n = s.size(), ans = 0;
        for(int i = 0; i < 2*n-1; i++){
            int l = i/2, r = i/2+i%2;
            while(l>=0&&r<n && s[l]==s[r]){
                l--; r++; ans++;
            }
        }
        return ans;
    }
};