poj 1754 Buffer Manager

#include <stdio.h>#define SIZE 100010#define MAX 0x7fffffffint f1[SIZE] = {0};int f2[SIZE] = {0};int a[SIZE];int main(){    int i, j, n, k;    int pos, min, temp;    char ch;    scanf("%d%d", &n, &k);    min = MAX;    for (i = 1; i <= n; i++)    {        scanf("%c", &ch);        if (ch == 'n')        { i--;        }        else if (ch == '*')        { a[i] = -1;        }        else        { a[i] = ch - '0'; f2[i] = f2[i-1] + a[i]; f1[i] = f1[i-1] + 1;  if (f1[i] >= k) {     temp = f2[i] - f2[i-k];     if (temp < min)     {         min = temp;         pos = i - k + 1;     } }        }    }    if (min == MAX)    {        printf("0n");    }    else    {        printf("%dn", pos);    }    return 0;}