f1 = file('in20_2.txt' , 'r') p=f1.readlines() no_of_exp=p[0] exp1=p[1] exp2=p[2] exp3=p[3] def rpn(e): prece={'-': 1, '+': 2, '/': 3, '*': 4, '#': 5} res=[] stk=[] i=0 while i96 and ord(e[i])<123): res.append(e[i]) i=i+1 elif e[i]==')': while not(stk[len(stk)-1]=='('): res.append(stk[len(stk)-1]) stk.pop() stk.pop() i=i+1 else: stk.append(e[i]) i=i+1 return res result=[] result.append(rpn(exp1)) result.append(rpn(exp2)) result.append(rpn(exp3)) print result f2=open('out_12_sec20_2.txt', 'w') for k in range(0,len(result)): for l in range(0,len(result[k])): f2.write(result[k][l]) f2.write('\n') f1.close f2.close