# Practice on Toph

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## Find NSUPS

Given a string `$s$`

, find the number of subsequence in `$s$`

which forms the word “NSUPS”. A subsequence is a sequence that can be derived from the string `$s$`

by deleting some characters from it without changing the order of the remaining characters. You have to find the number of subsequences exists in the string `$s$`

which is equal to “NSUPS”.

For example, let’s say `$s$`

= “NNSUUPS”. There are total four ways to select a subsequence equal to “NSUPS” from the string `$s$`

. Those subsequences are “N_SU_PS”, “N_S_UPS”, “_NSU_PS” and “_NS_UPS”.

#### Input

The first line contains an integer `$N$`

which denotes the length of the string `$s$`

. The second line contains the string `$s$`

consisting of uppercase English alphabets.

#### Constraints:

`${1 \leq N \leq 1000}$`

#### Output

Print the answer in a single line.

#### Samples

Input | Output |
---|---|

7 NNSUUPS | 4 |

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