Codeforces Round #296 (Div. 2) B. Error Correct System

[code]#include<algorithm>
#include<iostream>
#include<string>
#include<cstdio>
#include<cstring>
#include<queue>

using namespace std;

int p[28][28];
int n;
int num = 0;
string s, t;

int main()
{

    while (cin >> n)
    {
        cin >> s >> t; 
        memset(p, 0, sizeof(p)); num = 0;
        for (int i = 0; i < n; ++i)
        {
            if (s[i] != t[i])
            {
                p[s[i] - 'a'][t[i] - 'a'] = i + 1;
                num++;
            }
        }
        for (int i = 0; i < 26; ++i)
        {
            for (int j = 0; j < 26; ++j)
            {
                if (p[i][j] && p[j][i])
                {
                    cout << (num - 2) << endl;
                    cout << p[i][j] << " " << p[j][i] << endl;
                    return 0;
                }
            }
        }
        for (int i = 0; i < 26; ++i)
        {
            for (int j = 0; j < 26; ++j)
            {
                if (p[i][j])
                {
                    for (int k = 0; k < 26; ++k)
                    {
                        if (p[k][i])
                        {
                            cout << (num - 1) << endl;
                            cout << p[i][j] << " " << p[k][i] << endl;
                            return 0;
                        }
                    }
                }
            }
        }
        cout << num << endl;
        cout << "-1 -1" << endl;
    }
    return 0;
}