#include <bits/stdc++.h>
int main(void) {
  char S[100];
  int num, i = 0, sum, A[100];
  while (scanf("%s", S) != EOF) {
    num = S[0];
    if ('-1' < num && num < '10') {
      A[i] = atol(S);
      i++;
    } else {
      switch (num) {
        case '+':
          sum = A[i - 1] + A[i - 2];
          break;
        case '-':
          sum = A[i - 1] - A[i - 2];
          break;
        case '*':
          sum = A[i - 1] * A[i - 2];
          break;
        default:
          break;
      }
      A[i - 2] = num;
      i++;
    }
  }
  printf("%ld\n", A[0]);
  return 0;
}
