B"Timur initially had a binary string ^{ dagger} s (possibly of length 0 ). He performed the following operation several (possibly zero) times: ^{ dagger} A binary string is a string (possibly the empty string) whose characters are either texttt{0} or texttt{1} . The first line of the input contains an integer t ( 1 <= q t <= q 100 ) -- the number of testcases. The first line of each test case contains an integer n ( 1 <= q n <= q 2000 ) -- the length of Timur's final string. The second line of each test case contains a string s of length n consisting of characters texttt{0} or texttt{1} , denoting the final string. For each test case, output a single nonnegative integer -- the shortest possible length of Timur's original string. Note that Timur's original string could have been empty, in which case you should output 0 . In the first test case, the shortest possible string Timur started with is texttt{0} , and he performed the following operation: texttt{0} to color{red}{ texttt{1}} texttt{0} color{red}{ texttt{0}} . In the second test case, the shortest possible string Timur started with is texttt{11} , and he performed the following operation: texttt{11} to color{red}{ texttt{0}} texttt{11} color{red}{ texttt{1}} . In the third test case, the shortest possible string Timur started with is texttt{10101} , and he didn't perform any operations. In the fourth test case, the shortest possible string Timur started with is the empty string (which we denote by varepsilon ), and he performed the following operations: varepsilon to color{red}{ texttt{1}} texttt{} color{red}{ texttt{0}} to color{red}{ texttt{0}} texttt{10} color{red}{ texttt{1}} to color{red}{ texttt{1}} texttt{0101} color{red}{ texttt{0}} . In the fifth test case, the shortest possible string Timur started with is texttt{101} , and he performed the fol"...