int foo ( int A[], int n ) {
    int k, m, lsum, rsum; 
    for(k = 0; k < n; ++k) { 
        lsum = 0; rsum = 0;
        for(m = 0; m < k; ++m) lsum += A[m]; 
        for(m = k + 1; m < n; ++m) rsum += A[m];  
        if (lsum == rsum) return k;
    } 
    return -1; 
}  


##</code><code>##

int foo(int arr[], int n) {
    if (n==0) return -1; 
    long long sum = 0;
    int i; 
    for(i=0;i<n;i++) sum+=(long long) arr[i]; 

    long long sum_left = 0;    
    for(i=0;i<n;i++) {
        long long sum_right = sum - sum_left - (long long) arr[i];
        if (sum_left == sum_right) return i;
        sum_left += (long long) arr[i];
    } 
    return -1; 
}