#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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