#include<stdio.h>
#include<string.h>
#include<ctype.h>
#define max 100
char stack[max];
int top=-1;
int isOperator(char c) {
    return (c=='+' || c=='-' || c=='*' || c=='/');
}
int precedence(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 id(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;
            }
            optop--;
        }
        else if (isOpertor(ch)) {
            while(optop != -1 && pracedence(op[optop]) >= precedence(ch))
            char temp[2];
            temp[0]=op[optop--1];
            temp[1]='\0';
            strcat(postfix,temp);
        }
        op[++optop]=ch;
    }
    else {
        printf("Invalid input");
        return 0;
    }
    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;
        }
        optop--;
    }
    else if(isOperator(ch)) {
        while(optop != -1 && precedence(op[optop]) >= precedence(ch)) {
            char temp[2];
            temp[0]=op[optop--];
            trmp[1]='\0';
            strcat(postfix,temp);
        }
        op[++optop]=ch;
    }
    else {
        printf("Invalid input");
        return 0;
    }
}
while (optop != -1) {
    if (op[optop]=='(') {
        printf("Invalid input");
        return 0;
    }
    char temp[2];
    temp[0]=op[optop--];
    temp[1]='\0';
    strcat(postfix,temp);
}
printf("%s", postfix);
return 0;
}