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

int top,S[1000];

void push(int);
int pop();

int main(){

  int x,y;
  top=0;
  char s[100];

  while( scanf("%s",s) != EOF){
    if( s[0] == '+'){
      x = pop();
      y = pop();
      push(x+y);
    }
    else if( s[0] == '-'){
      x = pop();
      y = pop();
      push(y-x);
    }
    else if( s[0] == '*'){
      x = pop();
      y = pop();
      push(x*y);
    }
    else push(atoi(s));
  }
  printf("%d\n",pop());
  return 0;
}

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

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

