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

int top, S[1000];
void push(int);
int pop(void);

int main(){
  int x, y;
  char s[100];
  top = 0;
  while(scanf("%s",s) != EOF){
    if(s[0] == '+'){
      x = pop();
      y = pop();
      push(x + y);
    }
    else if(s[0] == '-'){
      y = pop();
      x = pop();
      push(x - y);
    }
    else if(s[0] == '*'){
      x = pop();
      y = pop();
      push(x * y);
    }
    else push(atoi(s));
  }

  printf("%d\n",pop());
  return 0;
}

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

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

