Sort

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

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int t;
    cin >> t;
    while (t--) {
        int n, q;
        cin >> n >> q;

        string a, b;
        cin >> a >> b;

        vector<vector<int>> freqa(n, vector<int>(26, 0)), freqb(n, vector<int>(26, 0));

        freqa[0][a[0] - 'a'] = 1;
        freqb[0][b[0] - 'a'] = 1;

        for (int i = 1; i < n; i++) {
            freqa[i] = freqa[i - 1];
            freqa[i][a[i] - 'a']++;
        }

        for (int i = 1; i < n; i++) {
            freqb[i] = freqb[i - 1];
            freqb[i][b[i] - 'a']++;
        }

        while (q--) {
            int l, r;
            cin >> l >> r;
            l--;
            r--;

            int sum = 0;
            for (int i = 0; i < 26; i++) {
                int v1 = (l == 0) ? freqa[r][i] : freqa[r][i] - freqa[l - 1][i];
                int v2 = (l == 0) ? freqb[r][i] : freqb[r][i] - freqb[l - 1][i];
                sum += abs(v1 - v2);
            }
            cout << sum / 2 << endl;
        }
    }

    return 0;
}