#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
int top, S[100];
 
void push(int x){
  S[++top] = x;
}
 
int pop(){
  top--;
  return S[top+1];
}
 
int main(){
  int a, b, x, no, np;
  top = 0;
  char s[100];
  no = np = 0;
  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      a = pop();
      b = pop();
      push(a + b);
      no++;
    } else if ( s[0] == '-' ){
      b = pop();
      a = pop();
      push(a - b);
      no++;
    } else if ( s[0] == '*' ){
      a = pop();
      b = pop();
      push(a * b);
      no++;
    } else {
      x = atoi(s);
      push(x);
      np++;
    }
  }
 
  printf("%d\n", pop());
 
  return 0;
}