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

int top, S[1000];

int main() {
    int a,b;
    top = 0;
    char s[100];
    
    while(1) {
        if (scanf("%s", s)==EOF) {
            break;
        }
        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;
}

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

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