#include <iostream>
using namespace std;
 
int main() {
	// Introduc variabilele a, b, c şi x;
	int a, b, c, x;
	// Citesc a, b, c, x;
	cin >> a >> b >> c >> x;
	if (c == x % 10) {// verificam "c"
 
 
	// Introduc variabila “cnt” sa numar cifrele;
	int cnt = 0;
	// parcurg x;
	int x_copy;
	while (x > 0) {
			++cnt;
		x_copy = x;// verificam "b"
		x /= 10;
 
	}
		if (b == x_copy)
		cout << b;
		//cout << cnt;// verificam "a"
	}
 
	return 0;
}

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