#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#include<string.h>
#define MAX_SIZE 1000
typedef struct{
    char array[MAX_SIZE];
    int top;
}
CharStack;
void initStack(CharStack*stack){
    stack->top=-1;
}
void push(CharStack*stack,char value){
    if(stack->top<MAX_SIZE-1){
        stack->array[++(stack->top)]=value;
    }
}
char pop(CharStack*stack){
    if(stack->top>=0){
        return stack->array[(stack->top)--];
    }
    return '\0';
}
int isEmpty(CharStack*stack){
    return stack->top==-1;
}
int isOperator(char c){
    return c=='+' || c=='*' || c=='/' || c=='^';
}
char*prefixToPostfix(const char*expression){
    static char result[MAX_SIZE];
    CharStack stack;
    initStack(&stack);
    int j=0;
    for(int i=strlen(expression)-1;i>=0;i--){
        char c=expression[i];
        if(isspace(c)){
            continue;
        }
        if(isalnum(c)){
            push(&stack,c);
        }
        else if(isOperator(c)){
            if(stack.top<1){
                return "Invalid input";
            }
            char op1=pop(&stack);
            char op2=pop(&stack);
            result[j++]=op1;
            result[j++]=op2;
            result[j++]=c;
            push(&stack,result[j-1]);
        }
        else{
        return"Invalid input";
      }
    }
    while(!isempty(&stack)){
        result[j++]=pop(&stack);
    }
    result[j]='\0';
    for(int k=0;k<j/2;k++){
        char temp=result[k];
        result[k]=result[j-k-1];
        result[j-k-1]=temp;
    }
    return result;
}
int main(){
    char prefixExpression[MAX_SIZE];
    fgets(prefixExpression,sizeof(prefixExpression),stdin);
    size_t len=strlen(prefixExpression);
    if(len>0 && prefixExpression[len-1]=='\n'){
        prefixExpression[len-1]='\0';
    }
    char*postfixExpression=prefixToPostfix(prefixExpression);
    printf("%s\n",postfixExpression);
    return 0;
}