There are $37$ pupils line up and say numbers in turn. The first pupil says $1$, and everyone after him says a number by adding $$3$$ to the previous number. Someone makes a mistake by subtracting instead of adding $3$ to the previous number. All the numbers said by these $37$ pupils add up to $2011$. Who makes the mistake? 
Overseas Competition->Knowledge Point->Calculation Modules->Sequences and Number Tables