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

void apply(char);
void load_num(char);
void load_var(char);
void store_var(char);

int yyerror(char *);
int yylex();
int reg_count=0;
struct instruction {
    char op1;
    char op2;
    char opr;
};
%}

%token IDENT NUM
%type expr
%left '+'
%left '*''/'
%left '-'
%%

statement: IDENT '=' expr ';' { store_var((char)$1); }
         ;

expr: expr '+' expr {apply('+');}
    | expr '-' expr {apply('-');}
    | expr '*' expr {apply('*');}
    | NUM {load_num((char)$1); $$=(char)$1;}
    | IDENT {load_var((char)$1); $$=(char)$1;}
    ;

%%

void apply(char opr) {
    switch(opr) {
        case '+': 
            printf("ADD ");
            break;
        case '-': 
            printf("SUB ");
            break;
        case '*': printf("MUL ");
    }
    printf("R%d, R%d, R%d\n", reg_count-2, reg_count-2, reg_count-1);
}

void load_num(char num) {
    printf("LD R%d, #%c\n", reg_count++, num);
}

void load_var(char var) {
    printf("LD R%d, %c\n", reg_count++, var);
}

void store_var(char var) {
    printf("ST %c, R%d\n", var, reg_count-1);
}

int yyerror(char *s) {
    printf("ERROR: %s",s);
    exit(0);
}

int main() {
    yyparse();
}