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

int pop(void);
void push(int);

int S[200],top = 0;

int main(){
  int x,a,b;
  char s[100];

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      a = pop();
      b = pop();
      push(a+b);
    }
    else if ( s[0] == '-' ){
      a = pop();
      b = pop();
      push(b-a);
    }
    else if ( s[0] == '*' ){
      a = pop();
      b = pop();
      push(a*b);
    }
    else {
      x = atoi(s);
      push(x);
    }
  }

  printf("%d\n",pop());

  return 0;
}

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

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

