#include<stdio.h>
#include<ctype.h>

#define STACK 10

 int main()
{
  
  int stack[STACK]; 
  int stack_n; 
  int sum; 
  int digit_f;
  int k; 
  char ch; 
  
  stack_n = 0;
  digit_f = 0;
 
  while( (ch = getchar()) != '\n' ) { 
    if( isdigit(ch) ) { 
      if( digit_f ) {
	stack[stack_n] = stack[stack_n] * 10 + (ch - '0'); 
      } else {
	stack[stack_n] = (ch - '0');
	digit_f++;
      }
    }
    if( isspace(ch) ) {
      if( digit_f ) {
	stack_n++;
	digit_f = 0;
      }
    }
    if( ch == '+' ) {
      if( stack_n > 1 ) {
	stack_n--;
      }
      stack[stack_n-1] += stack[stack_n];
      stack[stack_n] = 0;
    }
    if( ch == '-' ) {
      if( stack_n > 1 ) {
	stack_n--;
      }
      stack[stack_n-1] -= stack[stack_n];
      stack[stack_n] = 0;
    }

    if( ch == '*' ) {
      if( stack_n > 1 ) {
	stack_n--;
      }
      stack[stack_n-1] *= stack[stack_n];
      stack[stack_n] = 0;
    }
  }

  printf("%d\n",stack[0]);
  
  return 0;
}

