#include <vector>
#include <string>

int knuth_morris_pratt(const std::string text, const std::string pattern) {
	int n = text.length(), m = pattern.length();
	std::vector<int> next(m, 0);
	for (int i = 1, j = 0; i < m; i++) {
		while (j > 0 && pattern[i] != pattern[j]) {
			j = next[j - 1];
		}
		if (pattern[i] == pattern[j]) {
			j++;
		}
		next[i] = j;
	}

	for (int i = 0, j = 0; i < n; i++) {
		while (j > 0 && text[i] != pattern[j]) {
			j = next[j - 1];
		}
		if (text[i] == pattern[j]) {
			j++;
		}
		if (j == m) {
			return i - m + 1;
		}
	}
	return -1;
}