import java.io.*;
class Main {
in.nextToken();
return in.nval;
}
double a, b;
a = nextDouble();
b = nextDouble();
double t = (175*a - 75*b) / 100;
double v = 75 / (a - t);
double v0 = (50 - v*t) / t;
System.
out.
printf("%.6f", v0
); }
}
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