Envío 2360

Código

#include<bits/stdc++.h>
using namespace std;

int main(){
    string see;
    cin >> see;
    int k;
    cin >> k;
    map<char,int> counter;
    int ans = 0;
    for(int i = 0, j = 0; j < see.size();++j){
        ++counter[see[j]];
        while((int)counter.size() > k){
            --counter[see[i]];
            if(counter[see[i]] == 0)
                counter.erase(see[i]);
            ++i;
        }
        ans = max(ans,j-i+1);
    }
    printf("%d\n",ans);
    return 0;
}