#include <stdio.h>
int a[500],head=0;
int main(){
  int b,num=0;
  char c,d;
   
  while( (scanf("%c",&c))!=EOF){ 
    if(num==0&&c=='0'){ a[head]=num;
      head++;}
 
    if(c<='9'&&c>='0'){num=c-'0'+num*10;}      
    else if(num!=0){  
      a[head]=num;
      head++;
      num=0;
    }
    else {num=0;
      if(c=='+'){
        a[head-2]+=a[head-1];
        head--;
      }
      else if(c=='*'){
        a[head-2]*=a[head-1];
        head--;
      }
 
      else if(c=='-'){
        a[head-2]-=a[head-1];
        head--;
      }
    }  
  }
     
  printf("%d\n",a[head-1]);  
 
  return 0;
}