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

int main() {
  char* src = "1 2 + 4 5 + * 3 /";

  int ns[256];
  int ni;

  char cs[16];
  int ci;

  int i;
  char c;
  int l;
  
  int n1;
  int n2;

  ni = 0;
  ci = 0;
  l = strlen(src);
  for (i = 0; i < l; i++) {
    c = src[i];
    if (c == ' ') {
      if (ci > 0) {
        cs[ci] = '\0';
        ns[ni++] = atoi(cs);
        ci = 0;
      }
    } else if (isdigit(c)) {
      cs[ci++] = c;
    } else if (c == '+') {
      n2 = ns[--ni];
      n1 = ns[--ni];
      ns[ni++] = n1 + n2;
    } else if (c == '-') {
      n2 = ns[--ni];
      n1 = ns[--ni];
      ns[ni++] = n1 - n2;
    } else if (c == '*') {
      n2 = ns[--ni];
      n1 = ns[--ni];
      ns[ni++] = n1 * n2;
    } else if (c == '/') {
      n2 = ns[--ni];
      n1 = ns[--ni];
      ns[ni++] = n1 / n2;
    }
  }
  
  printf("expression %s\n", src);
  if (ni > 0) {
    printf("result %d\n", ns[--ni]);
  } else {
    printf("result %s\n", src);
  }
  
  return 0;
}