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

void push(int);
int pop();

int top,S[1000];

int main(){
  int x,y;
  top=0;
  char a[100];

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

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

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

