25 lines
502 B
Python
25 lines
502 B
Python
def weight(c):
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return ord(c)-ord('a')+1
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def main():
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n, k, = [int(i) for i in input().split()]
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string = [i for i in input()]
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string.sort(key=weight)
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total_weight = 0
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last_weight = -1
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curr = 0
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for i in string:
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if curr == k:
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break
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if weight(i) > last_weight+1:
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total_weight += weight(i)
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last_weight = weight(i)
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curr += 1
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if curr == k:
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print(total_weight)
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else:
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print(-1)
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main() |