18 lines
276 B
C
18 lines
276 B
C
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#include <stdio.h>
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int main(void){
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int number,n[105],i,s,m;
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scanf("%d",&number);
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for(i = 0; i < number; i++){
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scanf("%d",&n[i]);
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}
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scanf("%d %d",&s,&m);
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double avg = 0.0;
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for(i = s; i <= m; i++){
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avg += n[i];
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}
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avg /= m-s+1;
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printf("%lf\n",avg);
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return 0;
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}
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