#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int top, S[1000];
 
 
void push(int x){
    top++;
    S[top] = x;
}
 
int pop(){
    top--;
    return S[top+1];
}
 
 
int main(void) {
    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;
}