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

#define N 200
 
int main(){

  char c[N];
  int s[N], top = 0;
  int x, y;
 
  while(scanf("%s", c) != EOF){
    if(c[0] == '+'){
      top = top-1;
      x = s[top+1];
      top = top-1;
      y = s[top+1];
      top++;
      s[top] = x + y;
    }

    else if(c[0] == '-'){
      top = top-1;
      x = s[top+1];
      top = top-1;
      y = s[top+1];
      top++;
      s[top] = y - x;
    }

    else if(c[0] == '*'){
      top = top-1;
      x = s[top+1];
      top = top-1;
      y = s[top+1];
      top++;
      s[top] = x * y;
    }

    else{
      x = atoi(c); 
      top++;
      s[top] = x;
    }
  }

  printf("%d\n", s[top]);

  return 0;
}