PROGRAMMING:Quadratic equation with one variable (with real roots)

Input the values of three coefficients a, B and C of quadratic equation of one variable, and output its two roots (assuming that the equation has real roots). It is required that the big root output first and the small root output later.
###Input format:
Three numbers.
###Output format:
Output in sample format.
###Input example:
```in
1 4 3
```
###Output example:
```out
X1=-1.000
X2=-3.000
```
###Input example:
```in
1 2 1
```
###Output example:
```out
X1=-1.000
X2=-1.000
```







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