```python
def take_back(values: list, target: int) -> int:
    total = 0
    count = len(values)
    
    for i in range(len(values) - 1, -1, -1):
        if total >= target:
            return count - (i + 1)
        
        total += values[i]
        count -= 1
    
    return -1
```