import { WriteStream, createWriteStream } from 'fs'; import { stdin, stdout } from 'process';

// Function to count special substrings function substrCount(n: number, s: string): number { let count = 0;

// Count all uniform substrings
let i = 0;
while (i < n) {
    let length = 1;
    while (i + 1 < n && s[i] === s[i + 1]) {
        length++;
        i++;
    }
    count += (length * (length + 1)) / 2;
    i++;
}

// Count all substrings of the form where one character is different in the middle
for (let i = 1; i < n - 1; i++) {
    let length = 0;
    while (i - length >= 0 && i + length < n && s[i - length] === s[i + length] && s[i - length] !== s[i]) {
        count++;
        length++;
    }
}

return count;

}

// Main function to handle input and output function main() { const inputLines: string[] = [];

stdin.setEncoding('utf-8');
stdin.on('data', (chunk: string) => {
    inputLines.push(...chunk.trim().split('\n'));
});

stdin.on('end', () => {
    const outputStream: WriteStream = createWriteStream(process.env['OUTPUT_PATH'] || '/dev/stdout');

    const n: number = parseInt(inputLines[0].trim(), 10);
    const s: string = inputLines[1].trim();

    const result: number = substrCount(n, s);

    outputStream.write(result + '\n');
    outputStream.end();
});

}

main();