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

void push();
int pop();

int top,S[1000];

int main(){

  char s[100];
  int x,y;
  
  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 p){
  
  S[++top] = p;

}

int pop() {

  top--;

  return S[top+1];

}