#include <stdio.h>
#include<ctype.h>
#include<string.h>
#define MAX 100
char stack[MAX];
int top=-1;
void push(char c){
    stack [++top]=c;
}
char pop(){
    return stack[top--];
}
char peek(){
    return stack[top];
}
int precedence(char c){
    if(c=='+'|| c=='-')return 1;
    if(c=='*'|| c=='/')return 2;
    return 0;
}
int isOperator(char c){
    return (c=='+'|| c=='-'||c=='*'||c=='/');
}
int main(){
    char infix[MAx],postfix[MAX];
    int i,k=0;
    int balance=0;
    scanf("%s",infix);
    for(int i=0;infix[i] !='\0';i++){
        char ch=infix[i];
        if(isalnum(ch)){
            postfix[k++]=ch;
        }
        else if(ch =='('){
            push(ch);
            balance++;
        }
        else if(ch==')'){
            balance--;
            if(balance<0){
                printf("Invalid input");
                return 0;
            }
            while (top !=-1&& peek()!='('){
                postfix[k++]=pop();
            }
            pop();
        }
        else if(isOperator(ch)){
            while(top !=-1 && precedence(peek())>=precedence(ch)){
                postfix[k++]=pop();
            }
            push(ch);
        }
        else {
            printf("Invalid input");
            return 0;
        }
    }
    if(balance !=0){
        printf("Invalid input");
        return 0;
    }
    while(top !=-1){
        if(peek()==')'){
            printf("Invalid input");
            return 0;
        }
        postfix[k++]=pop();
    }
    postfix[k]='\0';
    printf("%s",postfix);
    return 0;
}