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

int top,S[1000];

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

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

int main(){
    int a,b;
    top=0;
    char s[100];
    while(scanf("%s",s)!=EOF){
        if(s[0]=='+'){
            a = pop();
            b = pop();
            push(b+a);
        }
        else if(s[0]=='-'){
            a = pop();
            b = pop();
            push(b-a);
        }
        else if(s[0]=='*'){
            a = pop();
            b = pop();
            push(b*a);
        }
        else push(atoi(s));
    }
    
    printf("%d\n",pop());
    //printf("%d %d ",S[1],S[2]);
    
    return 0;
}

