#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<ctype.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='/'|| 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;
    }