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

int top,P[1000000];

int main() {
  int a,b,c;
  char x[100];
  top=0;

  while(1) {
    if(scanf("%s",x[0] == EOF)) break;

    if(x[0] == '+'){
      a=pop();
         b=pop();
         push(a+b);
    }
    else if(x[0] == '-'){
      a=pop();
      b=pop();
      push(a-b);
    }
    else if(x[0] == '*'){
        a=pop();
        b=pop();
        push(a*b);
    }
    else {
         c=atoi(x);
         push(c);
    }
  }

  printf("%d\n",pop());

  return 0;
}

void push(int x) {
  P[++top] = x;
}

 int pop() {
   top--;

   return P[top+1];
 }