#include<stdio.h>
#include<stdlib.h>
#include<string.h>
 
int main(void){
  int i = 0;
  int stack[100];
  char s[100];
 
  while(scanf("%s", s) != EOF){
    if (s[0] == '+'){
      stack[i-2] = stack[i-2] + stack[i-1];
      i--;
    } 
    else if(s[0] == '-'){
      stack[i-2] = stack[i-2] - stack[i-1];
      i--;
    } 
    else if(s[0] == '*'){
      stack[i-2] = stack[i-2] * stack[i-1];
      i--;
    }
    else{
      stack[i] = atoi(s);
      i++;  
    }
  }
  printf("%d\n",stack[0]);

  return 0;
}