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

string expr;
int pos = 0;

int peek() { return expr[pos]; }
void next() { pos++; }

int parse_expr();

int parse_factor() {
  int val = 0;
  if (peek() == '(') {
    next();
    val = parse_expr();
    if (peek() != ')') { printf("syntax error: expected )\n"); return 0; }
    next();
    return val;
  }
  while (peek() >= '0' && peek() <= '9') {
    val = val * 10 + (peek() - '0');
    next();
  }
  return val;
}

int parse_term() {
  int val = parse_factor();
  while (peek() == '*' || peek() == '/') {
    char op = peek(); next();
    int rhs = parse_factor();
    if (op == '*') val = val * rhs; else val = val / rhs;
  }
  return val;
}

int parse_expr() {
  int val = parse_term();
  while (peek() == '+' || peek() == '-') {
    char op = peek(); next();
    int rhs = parse_term();
    if (op == '+') val = val + rhs; else val = val - rhs;
  }
  return val;
}

int main() {
  printf("Enter expression: ");
  scanf("%s", &expr);
  int result = parse_expr();
  printf("= %d\n", result);
  return 0;
}