#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] == '*'){
            
            a = pop();
            b = pop();
            push(a*b);
            
        }else{
            
            push(atoi(s));
            
        }
        
    }
    
    printf("%d\n",pop());
    
    return 0;
}
