#include <iostream>
using namespace std;
 
double x[3][20] = {{0.0}}; 
 
int main() {
	x[0][0] = .4;
	x[1][0] = .4;
	x[2][0] = .2;
	double ans = 1.0;
	for(int i = 1; i < 10; i++) {
		x[0][i] = .5 * (x[0][i-1] + x[1][i-1]);
		x[1][i] = .25 * (x[0][i-1] + x[1][i-1]) + x[2][i-1];
		x[2][i] = .25 * (x[0][i-1] + x[1][i-1]);
 
		ans += .5 * x[1][i-1];
		ans += .25 * x[0][i-1] + x[2][i-1];
		ans += .25 * (x[0][i-1] + x[1][i-1]);
	}
	cout << ans;
	return 0;
}

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