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

int top,S[1000];

void push(int x){
 
   top++;
   S[top] = x;
   // printf("%d",x);
 }

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


int main(){
  int a,b;
  top=0;
  char s[100];

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

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

  return 0;
}

