#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],pstfix[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(ch);
    }
    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",posfix);
return 0;
}

    }
}
}