Problems

# School concert

# School concert

At the school concert **a** students sang, **b** students danced, and **c** students sang and danced. How many participants were there in total?

#### Input

Three positive integers **a**, **b** and **c** (**a**, **b**, **c** ≤ `10`

).^{18}

#### Output

Print the number of participants at the school concert.

Input example #1

13 9 5

Output example #1

17