#include<stdio.h>
#include<string.h>
#include<ctype.h>
#define MAX 100000
char stack[MAX];
int top=-1;
void push(char c){
    if(top < MAX -1 ){
        stack[++top]=c;
    }
}
char pop(){
    if(top >=0){
        return stack[top--];
    }
    return -1;
}
char peek(){
    if(top >=0) return stack[top];
    return -1;
}
int isOpening(char c){
    return(c == '(' || c =='[' || c == '{');
}
int isClosing(char open, char close) {
    return(c == ')' || c ==']' || c == '}');
}
int isMatching(char open,char close){
    return((open == '(' && close == ')')||
           (open == '[' && close == ']')||
           (open == '{' && close == '}'));
}
int isAllowedchar(char c){
    return(isdigit(c) || c =='+'||c =='-'||c =='*'||c =='/'||
           c =='('|| c ==')'|| c =='[' || c ==']'||
           c =='{'|| c =='}'|| isspace(c));
}
int isValidsequence(char *exp){
    int len=strlen(exp);
    for(int i=0;i<len;i++){
        char c=exp[i];
        if(!isAllowedchar(c)){
            return -1;
        }
        if(isOpening(c)){
          push(c);
        }
        else if(isClosing(c)) {
            if(top ==-1 || !isMatching(pop(),c)){
                return 0;
            }
        }
    }
    if(top!=-1){
        return 0;
    }
    return -1;
}
int main(){
    char expression[MAX];
    if(!fgets(expression,sizeof(expression),stdin)){
        printf("Invalid input\n");
        return 0;
    }
    int result=isValidsequence(expression);
    if(result==-1){
        printf("Invalid input\n");
    }
    else if(result==0){
        printf("Invalid input\n");
    }
    else{
        printf("Invalid input\n");
    }
    return 0;
}