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

int main(){
  int x, stack[100], i=0;
  char s[100];
  
  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      stack[i-2] = stack[i-2] + stack[i-1];
      i -= 1;
    } else if ( s[0] == '-' ){
      stack[i-2] = stack[i-2] - stack[i-1];
      i -= 1;
    } else if ( s[0] == '*' ){
      stack[i-2] = stack[i-2] * stack[i-1];
      i -= 1;
    } else {
      x = atoi(s);
      stack[i] = x;
      i++;
    }
  }
  printf("%d\n", stack[0]);
  return 0;
}