#include <bits/stdc++.h>
using namespace std;
 
int main() {
	long long a, b, c, d;
	cin >> a >> b >> c >> d;
	long long max_num = a;
	if ( b > max_num ) {
		max_num = b;
	}
	if ( c > max_num ) {
		max_num = c;
	} 
	if ( d > max_num ) {
		max_num = d;
	}
	cout << max_num << endl;
	return 0;
}
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