这时求一个环的和非零数组的最大元素个数，我的运行到234ms wa了，高手帮忙看看，算法哪里有错。
#include"stdio.h"
int c[100001];
int main()
{
    int i,j,k,n,max=-1,sum,head,tail,m;
    int a,b;
    while(scanf("%d",&n)!=EOF)
    {    head=0;
        max=0;
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&a,&b);
            c[i]=a-b;
        }
        k=0;
        sum=0;m=0;
        for(i=0;i<n;i++)
        {

            if(i>=n)
            {
                m=1;
                i=0;
            }
            if(i==head&&m==1)
                break;
            sum+=c[i];
            if(sum<0)
            {
                head=i+1;
                sum=0;
                k=0;
            }
                k++;
            if(max<k)
                max=k;
        }
        printf("%d\n",max);
    }
    return 0;
}

大侠帮忙找找错呀