/* package whatever; // don't place package name! */
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.Stack;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
public static void main
(String[] args
) { Stack<Character> stk=new Stack<>();
char c1; char c2;
int c=0;
int l=input.length();
for (int i = 0; i < l; i++) {
if (input.charAt(i) == '{') {
stk.push(input.charAt(i));
}
if (input.charAt(i) == '}') {
if (stk.isEmpty()) {
stk.push(input.charAt(i));
} else if (stk.peek() == '{') {
stk.pop();
} else if (stk.peek() == '}') {
stk.push(input.charAt(i));
}
}
}
System.
out.
println(stk.
size()); }
}
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