public class Solution {
    /**
     * @param s A string
     * @return whether the string is a valid parentheses
     */
    public boolean isValidParentheses(String s) {
        // Write your code here
        if(s.length()==0){
			return false;
		}
		if(s.length()%2==1){
			return false;
		}
		Stack<Character> stack=new Stack<Character>();
		for(int i=0;i<s.length();i++){
			Character c=s.charAt(i);
			if(c!='('&&c!=')'&&c!='['&&c!=']'&&c!='{'&&c!='}'){
				return false;
			}
			if(c=='('||c=='{'||c=='['){
				stack.push(c);
			}else{
				if(stack.isEmpty()){
					return false;
				}
				if(c==')'){
					if(stack.peek()!='('){
						return false;
					}else{
						stack.pop();
					}
				}else if(c==']'){
					if(stack.peek()!='['){
						return false;
					}else{
						stack.pop();
					}
				}else{
					if(stack.peek()!='{'){
						return false;
					}else{
						stack.pop();
					}
				}
			}
		}
		if(!stack.isEmpty()){
			return false;
		}else{
			return true;
		}

    }
}