data.csv

num1,operation,num2,output,flag
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,wrong sign
0,,0,0,off by one
0,,0,0,wrong sign