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

int main(){
  int x,stack[100],i=0,ans=1;
  char s[100];

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      stack[i-2] += stack[i-1];
      i--;
    } else if ( s[0] == '-' ){
      stack[i-2] -= stack[i-1];
      i--;
    } else if ( s[0] == '*' ){
      stack[i-2] *= stack[i-1];
      i--;
    } else {
      stack[i++] = atoi(s);
    }
  }
  printf("%d\n",stack[0]);
  return 0;
}