Score : $1200$ points
In Takahashi's mind, there is always an integer sequence of length $2 \times 10^9 + 1$: $A = (A_{-10^9}, A_{-10^9 + 1}, ..., A_{10^9 - 1}, A_{10^9})$ and an integer $P$.
Initially, all the elements in the sequence $A$ in Takahashi's mind are $0$, and the value of the integer $P$ is $0$.
When Takahashi eats symbols +
, -
, >
and <
, the sequence $A$ and the integer $P$ will change as follows:
+
, the value of $A_P$ increases by $1$;-
, the value of $A_P$ decreases by $1$;>
, the value of $P$ increases by $1$;<
, the value of $P$ decreases by $1$.Takahashi has a string $S$ of length $N$. Each character in $S$ is one of the symbols +
, -
, >
and <
.
He chose a pair of integers $(i, j)$ such that $1 \leq i \leq j \leq N$ and ate the symbols that are the $i$-th, $(i+1)$-th, $...$, $j$-th characters in $S$, in this order.
We heard that, after he finished eating, the sequence $A$ became the same as if he had eaten all the symbols in $S$ from first to last.
How many such possible pairs $(i, j)$ are there?
+
, -
, >
or <
.Input is given from Standard Input in the following format:
$N$ $S$
Print the answer.
5 +>+<-
3
If Takahashi eats all the symbols in $S$, $A_1 = 1$ and all other elements would be $0$. The pairs $(i, j)$ that leads to the same sequence $A$ are as follows:
5 +>+-<
5
Note that the value of $P$ may be different from the value when Takahashi eats all the symbols in $S$.
48 -+><<><><><>>>+-<<>->>><<><<-+<>><+<<>+><-+->><<
475