Calculator Program

Write a calculator program that can perform addition, subtraction, multiplication, and division.

The input consists of several lines. Each line contains a number or one of the operators (+, -, *, /, =), given alternately. The first line is a number.

Operator precedence is ignored; the calculation is performed from left to right in the order the input is given. When = is given, print the result computed so far.

Each given number is a positive integer at most $10^8$. An intermediate result may be $0$ or negative, but it never leaves the range $-10^8 \sim 10^8$.

In division, the fractional part is discarded. For example, 100 / 3 * 3 = 99.

Division in which the dividend (the number being divided) is negative is never given as input.

Print the result of the calculation on the first line.