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

int main(){
  int x,t=0;
  char s[100],S[100];
  
  while( scanf("%s", &s[0]) != EOF ){
    if ( s[0] == '+' ){
      S[t-2]=S[t-2]+S[t-1];
      t-=1;
    } else if ( s[0] == '-' ){
      S[t-2]=S[t-1]-S[t-2];
      t-=1;
    } else if ( s[0] == '*' ){
      S[t-2]=S[t-2]*S[t-1];
      t-=1;
    }
    else{
      x = atoi(s);
      S[t] = x;
      t++;
    }
  }
  printf("%d\n",S[t-1]); 
 return 0;
}