// editor5
#include<stdio.h>
#include<ctype.h>
#define max 100
char stack[max];
int top=-1;
int isOperator(char c){
    return (c=='+' || c=='-' || c=='*' || c=='/');
    
}
int precendence(char ch){
    if(ch=='+' || ch=='-')return 1;
     if(ch=='*' || ch=='/')return 2;
    return 0;
}
int main(){
    char infix[max],postfix[max]="";
    char op[max];
    int optop=-1;
    scanf("%s",infix);
    for(int i=0;infix[i]='\0';i++){
        char ch=infix[i];
        if(isalnum(ch)){
            char temp[2];
            temp[0]=ch;
            temp[1]='\0';
            strcat(postfix,temp);
        }
        else if(ch=='('){
            op[++optop]=ch;
        }
        else if(ch=='('){
            while(!optop!=-1 && op[optop]!='('){
                char temp[2];
                temp[0]=op[optop--];
                temp[1]='\0';
                strcat(postfix,temp);
                
                 }
                 if(optop==-1){
                     printf("Invalid input");
                     
                 }
        }
    }
    return 0;
}