10

#include <iostream>
#include <math.h>
#include <algorithm>
#include <string>

using namespace std;

const int q = 65536;

int hashc(string s, int a, int b) {
    int n = b - a;
    int sum = 0;
    for (int i = 0; i < n; ++ i) {
        sum += s[a + i] * (int)pow(2, n - i - 1);
    }
    sum %= q;
    return sum;
}

int RABINKarp(string s, string t) {
    int n = s.size();
    int m = t.size();
    int h = hashc(t, 0, m);
    for (int i = 0; i < n - m + 1; ++ i) {
        if (h == hashc(s, i, i + m)) {
            bool eq = true;
            for (int j = 0; j < m; ++ j)
                if (s[i + j] != t[j])
                    eq = false;
            if (eq) return i;
        }
    }
    return -1;
}

int main() {
    string s, t;
    cin >> s >> t;
    cout << RABINKarp(s, t) << endl;
    return 0;
}