题解 | 小红的大小写字母

#include <bits/stdc++.h>

using namespace std;

int main() {
    long long n, k;
    string s;
    cin >> n >> k >> s;
    long long a = 0, b = 0;
    for (int i = 0; i < s.size(); i++) {
        if (s[i] >= 'a' && s[i] <= 'z') a++;
    }
    b = n - a;
    if (k > n) {
        if (k - a % 2 != 0) cout << n - 1;
        else cout << n;
    }
    else if (k <= a) cout << b + k;
    else {
        if (k - a % 2 == 0) cout << n - 1;
        else cout << n;
    }
    return 0;
}