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


int top = 0;
int A[1000];
void push(int);
int pop(void);

int main(){
  int x,y,p;
  char s[100];

  while( scanf("%s", s) != EOF ){
    if(*s < 48 || *s > 57){
      s[0] = *s;
    }
    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 h){
  A[++top] = h;
}

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

