#include <cstdio>
#include <cctype>
int gettype(char ch)
{
	if (ch == '+' || ch == '-' || ch == '*' || ch == '/') return 1;
	if (ch == '(' || ch == ')') return 2;
	if (ch >= 'a'&&ch <= 'c') return 3;
	return -1;
}
int main()
{
	char cur, prev = 0;
	int bracket = 0;
	while ((cur = getchar()) != ';')
	{
		if (gettype(cur) == 2) bracket = (cur == '(' ? bracket + 1 : bracket - 1);
		if (gettype(cur) == -1) { puts("ERROR 1"); return 0; }
		if ((gettype(cur) == gettype(prev) && gettype(cur) != 2) || (cur == '('&&gettype(prev) == 3) || (prev == ')'&&gettype(cur) == 3)) { puts("ERROR 3"); return 0; }
		if (bracket < 0) { puts("ERROR 2"); return 0; }
		prev = cur;
	}
	puts(bracket == 0 ? "OK" : "ERROR 2");
	return 0;
}