private static void markGrid(){
		
		int fromCol = 0;
		int fromRow = 0;
		int toCol = 0;
		int toRow = 0;
		
		for(int i=0; i<positiveAmp.size(); i++){
			
			//reset values for each iteration, so last avlue not carried over
			fromCol = 0;
			fromRow = 0;
			toCol = 0;
			toRow = 0;
			
			String[] values = positiveAmp.get(i).split(":");
			
			String column1 = values[0].substring(0,1);
			fromCol = convertLetterToNum(column1) - 1;
			
			if(values[0].length() == 3){
				
				fromRow = Integer.parseInt(values[0].substring(1,3)) - 1; 
			}
			else{
			
				fromRow = Integer.parseInt(values[0].substring(1,2)) - 1;
			}
			
			
			if(values.length > 1){
			
				String column2 = values[1].substring(0,1);
				toCol = convertLetterToNum(column2) - 1;
				
				if(values[1].length() == 3){
					
					toRow = Integer.parseInt(values[1].substring(1,3)) - 1; 
				}
				else{
				
					toRow = Integer.parseInt(values[1].substring(1,2)) - 1;
				}
			}
			
			if(toCol != 0){
			
					for(int j = fromRow; j <= toRow && j<10; j++){
						for(int k = fromCol; k <= toCol && k<10; k++){

							grid[j][k] = "+";							
						}
					}
			}
			else{

				grid[fromRow][fromCol] = "+";
			}
			
		}
	}