Find out which lead sources are making you money

You are a marketing analyst helping a car dealership evaluate the profitability of its lead sources. Use ONLY the data I provide below. Do not estimate, assume, or fill in any missing numbers.

MY LEAD SOURCE DATA:
(List each source with: name, monthly cost, number of leads, number of sales, and gross profit generated. Use the same time period for all sources — e.g., all Last Month, or all Quarter to Date — mixing periods across sources will produce a misleading comparison. Example:)
- Cars.com | $2,000 | 45 leads | 6 sales | $18,000 gross profit
- Edmunds | $1,200 | 30 leads | 3 sales | $8,100 gross profit
- Carfax | $800 | 20 leads | 2 sales | $5,200 gross profit

[Replace the example lines above with your real sources and numbers.]

STEP 0 — BEFORE DOING ANY CALCULATIONS:
Count how many lead sources were provided. If it is only 1 or 2, stop and display this message instead of proceeding:

"This tool is designed to evaluate all of your lead sources together, so you can see how they perform relative to each other — a holistic view. With only [1/2] source(s) entered, you won't get a meaningful comparison. Would you like to continue anyway with what you have, or add more sources first?"

Wait for the user's response before continuing. If they say to continue anyway, proceed with the calculations and output format below using only the source(s) provided. If 3 or more sources were provided from the start, skip this step entirely and go straight to the calculations.

CALCULATIONS TO PERFORM (internally, for every source):
- Cost per lead = Monthly cost ÷ Leads
- Cost per sale = Monthly cost ÷ Sales
- Marketing ROI = (Gross profit − Monthly cost) ÷ Monthly cost, as a percentage
- Return multiple = Gross profit ÷ Monthly cost, as "$X generated for every $1 spent"
- Flag any source with fewer than 10 leads OR fewer than 3 sales as "Limited data — treat with caution"
- If two sources tie on Marketing ROI, rank the one with more sales higher.
- Round all dollar figures to 2 decimal places and all percentages to the nearest whole percent.
- Recompute every metric a second way to check for errors before presenting anything. If any input is missing for a source, note exactly which metric can't be calculated and why — do not guess.

OUTPUT FORMAT — follow this structure exactly, in this order, with no other content before Section 1:

### 1. Ranked Results
A single table, ranked highest-to-lowest Marketing ROI, with columns: Rank | Source | Cost per Lead | Cost per Sale | Marketing ROI | Return Multiple | Status. Status is "Normal" for sources meeting both thresholds, or "Limited data — treat with caution" otherwise. Flagged sources get "—" for rank but still appear in the table.

### 2. Takeaway
2-3 plain-English sentences: which source is performing best, which is underperforming relative to its cost, and the ROI gap between the highest and lowest source. No advice, no budget recommendations — only what the numbers show.

### 3. Verification (condensed)
For each source, one line only: "[Source]: ROI recomputed via [Return Multiple − 1] × 100 = [result] ✓" or "✗ mismatch — recheck inputs" if the two methods disagree. Do not show the full recalculation work — just the confirmation line.

Do not add commentary, disclaimers, or sections beyond these three.