eli和字符串

#include <bits/stdc++.h>
#define inf 0x3f3f3f3f
#define INF 0x7fffffffffffffff

typedef long long ll;
const double PI=3.1415926535897931;
const long long mod=1e9+7;
const int MA= 1e7+10;
const int ma= 2*1e5+10;
const int few=1e3+10;
using namespace std;
//////////////////////////////////////////////

int main()
{

    int n,k,ans=inf;
    string s;
    cin>>n>>k;
    cin>>s;
    vector<int> a[26];
    for(int i=0; i<s.size(); i++)
    {
        int x=s[i]-‘a‘;
        a[x].push_back(i);
        int len=a[x].size();
        if(len>=k)
            ans=min(ans,i-a[x][len-k]+1);
    }
    if(ans==inf)
        cout<<"-1"<<endl;
    else
        cout<<ans<<endl;
    return 0;
}