Fibonacci Numbers Computation

This problem requires you to compute the nth Fibonacci number by implementing an iterative method. The Fibonacci sequence is defined as follows:

$$F(0)=0,\ F(1)=1,\ F(n)=F(n-1)+F(n-2) \text{ for } n\ge2$$

Your program should read an integer n from standard input and output the nth Fibonacci number to standard output. If the input is a negative number, the program should output the error message "Input cannot be negative".

inputFormat

The input consists of a single integer n provided via standard input. It is guaranteed that when n is non-negative, it falls within a reasonable range (for example, 0 ≤ n ≤ 40). When n is negative, your program must handle it appropriately.

outputFormat

If the input n is non-negative, output a single integer representing the nth Fibonacci number. If the input is negative, output the exact error message "Input cannot be negative".

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