#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

inline int power(int a, int b, int mod=M) {
    int x = 1;
    a %= mod;
    while (b) {
        if (b & 1) x = (x * a) % mod; 
        a = (a * a) % mod;
        b >>= 1;
    }
    return x;
}


//_ ***************************** START Below *******************************




string a;

int consistency(int n, int l, int r){
	
    vector<vector<bool>> dp(n, vector<bool>(n, false));
    vector<vector<int>> dpCt(n, vector<int>(n, 0));
    
    for(int gap=0; gap<n; gap++){
    	for(int i=0, j=gap; j<n; i++,j++){
    		if(gap == 0){
    			dp[i][j] = true;
    			dpCt[i][j] = 1;
    		}
    		else if(gap == 1){
    			if(a[i] == a[j]){
    				dp[i][j] = true;
    				dpCt[i][j] = 3;
    			}
    			else{
    				dpCt[i][j] = 2;
    			}
    		}
    		else{
    			dpCt[i][j] = dpCt[i][j-1] + dpCt[i+1][j] - dpCt[i+1][j-1];
    			
    			if(a[i] == a[j] && dp[i+1][j-1] ){
    				dp[i][j] = true;
    				dpCt[i][j]++;
    			}
    		}
    	}
    }
    

	return dpCt[l][r];
}















int practice(int n, int l, int r){


    return 0;
}





void solve() {
    
    int n, l, r;
    cin >> n >> l >> r;
    
    cin >> a;
    
    cout << consistency(n, l, r) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}