#include "testlib.h"
#include <bits/stdc++.h>

using namespace std;


vector<int> prefix_function(string s) {
    int n = (int)s.length();
    vector<int> pi(n);
    for(int i = 1; i < n; ++i) {
        int j = pi[i - 1];
        while(j > 0 && s[i] != s[j])
            j = pi[j - 1];
        if(s[i] == s[j])  ++j;
        pi[i] = j;
    }
    return pi;
}

vector<int> z_function(string s) {
    int n = (int)s.length();
    vector<int> z(n);
    for(int i = 1, l = 0, r = 0; i < n; ++i) {
        if(i <= r)
            z[i] = min(r - i + 1, z[i - l]);
        while(i + z[i] < n && s[z[i]] == s[i + z[i]])
            ++z[i];
        if(i + z[i] - 1 > r)
            l = i, r = i + z[i] - 1;
    }
    return z;
}

long long comp(string s){
    auto a = prefix_function(s);
    auto b = z_function(s);
    long long t = 0;
    for(int i = 0; i < s.size(); i++){
        t += 1ll * a[i] * b[i];
    }
    return t;
}


int main(int argc, char * argv[]){
    registerTestlibCmd(argc, argv);
    long long N = inf.readLong();
    long long K = inf.readLong();

    string G = ouf.readString();


    if(G.size() > K){
        quitf(_wa, "incorrect length of the string");
    }

    for(int i = 0; i < G.size(); i++){
        ensure(G[i] <= 'z' && G[i] >= 'a');
    }
    if(comp(G) == N){
        quitf(_ok, "ok");
    }
    else {
        quitf(_wa, "wa");
    }
}