// editor5
#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--];
}
int precedence(char c){
    if(c == '+' || c == '-')return 1;
    if(c == '+' || c == '/')return 2;
    return 0;
}
int main(){
    char infix[MAX],postfix[MAX];
    int i,k=0,balance=0;
    scanf("%s",infix);
    for(i=0;i<strlen(infix);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 && stack[top] != '('){
                postfix[k++] = pop();
            }
            pop();
        }
        else if(ch == '+' || ch == '-' || ch == '*' || ch == '')
    }
}