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

int main(){
  int x,i=0,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 {
      x = atoi(s);
      stack[i] = x;
      i++;
    }
  }
  printf("%d\n",stack[i-1]);  
  return 0;
}