#include <iostream>
#include <cstdlib>
using namespace std;

int main() {
	long s = 0;
	int MAXN = 10000000;
	for (int i=0;i<MAXN;i++){
		int q[] = {5,5,5,5,5,10,-1,-10};
		int p = 0;
		int t = 0;
		while (1){
			int o = rand()%8;
			p = q[o];
			if (p < 0 && p > -10){
				q[0] = q[1] = q[2] = q[3] = q[4] = 5;
				q[5] = 10;
				q[6] = -1;  //refresh 
				q[7] = -10; //x2
			}
			else {
				if (p <= -100)
					goto lab;
				if (p < 0){
					t*=2;
					for (int _=0;_<8;_++)
						q[_]*=2;
				} else t+=p;
				q[o] = -100; //empty
			}
		}
		lab: ;
		s+=(t>=100);
	}
	cout<< (s+0.0)/MAXN*100<<endl;
	return 0;
}