#include <iostream>
#include <string>

using namespace std;

// 牛客 数组中两个字符串最小距离
// 贪心 + 模拟
int main()
{
    string str1, str2;    
    string str;
    int ret = 0x3f3f3f3f;
    int n, prev1 = -1, prev2 = -1;
    cin >> n;
    cin >> str1 >> str2;
    for(int i = 0; i < n; i++)
    {
        cin >> str;
        if(str1 == str)
        {
            if(prev2 != -1)
            {
                ret = min(ret, i - prev2);
            }
            prev1 = i;
        }
        else if(str2 == str)
        {
            if(prev1 != -1)
            {
                ret = min(ret, i - prev1);
            }
            prev2 = i;
        }
    }
    if(ret == 0x3f3f3f3f) cout << -1 << endl;
    else cout << ret << endl;
}