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

//E -> TE' 
//E' -> +TE' | e
//T -> FT'
//T' -> *FT' | e
//F -> NUM | (E)
//FIRST(E) = {NUM, LEFTB}
//FIRST(E') = {PLUS, e}
//FIRST(T) = {NUM, LEFTB}
//FIRST(T') = {MULT, e}
//FIRST(F) = {NUM, LEFTB}
//FOLLOW(E) = {$, RIGHTB}
//FOLLOW(E') = {$, RIGHTB}
//FOLLOW(T) = {PLUS, RIGHTB, $}
//FOLLOW(T') = {PLUS, RIGHTB, $}
//FOLLOW(F) = {MULT, PLUS, RIGHTB, $}

enum TOKEN {PLUS, MULT, NUM, END, ERR, LEFTB, RIGHTB};
char lookahead;
enum TOKEN token;
int num;
int error = 0;
FILE *fp;

void lexical(FILE *fp);
int match(enum TOKEN x);
int E();
int E_();
int T();
int T_();
int F();


//return 0 if success, return 1 otherwise
int match(enum TOKEN x) {
	if(token == x) {
		lexical(fp);
		return 0;
	} else {
		error = 1;
		return 1;
	}
}

//E -> TE' 
int E() {
    T();
    E_();
	return 0;
}

//E_ -> +TE'|e 
int E_() {
	if(lookahead == '+')
	{  
	    lexical(fp);
		T();
		E_();
        return 0; 
    }

    else if(token==END||token==RIGHTB) return 0;
    else {error=1;token=ERR;return 1;}
}

//T -> FT'
int T() {
    F();
	T_();
	return 0;
}


//T' -> *FT' | e
int T_() {
	if(lookahead == '+')
        {
        	 lexical(fp);
              F();
			  T_();
			  return 0;
        }
   else if(token==PLUS||token==RIGHTB||token==END) return 1;
	else {error=1;token=ERR;return 0;}
}

//F -> NUM | (E)
int F() 
	 {
	 if(isdigit(lookahead))
    {
	   lexical(fp);
    }
    else if(lookahead == '(')
    {
    	lexical(fp);
        E();
        if(lookahead == ')')
           {
		   lexical(fp);
           }
        else {error=1;token=ERR;return 1;}
    }
    else {error=1;token=ERR; return 1;}
}





void lexical(FILE *fp) {

	lookahead = getc(fp);
	num = 0;

	while(lookahead == ' ' || lookahead == '\t' || lookahead == '\n') {
		lookahead = getc(fp);
	}

	if(isdigit(lookahead)) {
		num = 0;
		while(isdigit(lookahead)) {
			token = NUM;
			num = num * 10 + lookahead - '0';
			lookahead = getc(fp);
		}
		ungetc(lookahead, fp);
		return;
	} else if (lookahead == '+') {
		token = PLUS;
		return;
	} else if (lookahead == '*') {
		token = MULT;
		return;
	} else if(lookahead == EOF) {
		token = END;
		return;
	}else if(lookahead == '(') {
		token = LEFTB;
		return;
	} else if(lookahead == ')') {
		token = RIGHTB;
		return;
	} else {
		error = 1;
		token = ERR;
		return;
	}
}

int main(int argc, char **argv) {
	int  res = 0;
	if(argc < 2) {
		printf("insufficient arguments");
		return 1;
	}
	fp = fopen(argv[1], "r");

	lexical(fp);
	res = E();
	if(!error) {
		printf("%d\n", res);
	} else {
		printf("There are errors\n");
	}

	fclose(fp);
	return 0;

}