/******************************************************************************

                            Online C Compiler.
                Code, Compile, Run and Debug C program online.
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*******************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int top,S[1000];

void push(int x){
    S[++top] = x;
}

int pop(){
    top--;
    return S[top+1];
}

int main(){
    int a,b;
    top = 0;
    char s[100];
    
    while(scanf("%s",s) != EOF){
       if (s[0] == '+'){
           a = pop();
           b = pop();
           push(a+b);
        }else if (s[0] == '-'){
        b = pop();
        a = pop();
        push (a-b);
        }else if (s[0] == '*' ){
        b = pop();
        a = pop();
        push (a*b);
        } else {
            push(atoi(s));
        }    
    }
    
    printf("%d\n",pop());
    return 0;
}
