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def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    idx = 0
    n = int(data[idx])
    idx += 1
    m = int(data[idx])
    idx += 1
    
    queries = []
    for _ in range(m):
        l = int(data[idx])
        idx += 1
        r = int(data[idx])
        idx += 1
        queries.append((l, r))
    
    diff = [0] * (n + 2)
    for l, r in queries:
        diff[l] += 1
        if r + 1 <= n:
            diff[r + 1] -= 1
    
    freq = [0] * (n + 1)
    for i in range(1, n + 1):
        freq[i] = diff[i]
    
    freq.sort(reverse=True)
    
    a = [0] * (n + 1)
    current = n
    for i in range(1, n + 1):
        if freq[i] == 0:
            a[i] = 0
        else:
            a[i] = current
            current -= 1
    
    pre = [0] * (n + 1)
    for i in range(1, n + 1):
        pre[i] = pre[i - 1] + a[i]
    
    total = 0
    for l, r in queries:
        total += pre[r] - pre[l - 1]
    
    print(total)
if __name__ == "__main__":
    main()

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